Add a per-widget text-size picker for calendar/tasks legibility

Calendar and tasks pack the most body text at the smallest default
sizes, so those two gear-icon dialogs get a "Text size" card (Normal/
Large/X-Large) alongside the existing Border card -- a new Widget-level
font_scale column with its own POST .../font-scale endpoint, same
Widget-property-not-config-field shape as border_style. Threaded through
every classic (calendar_render.py) and modern (html_render.py/
calendar_html_render.py) size calc via one shared panel_style.
scaled_size() so row heights/max_rows already derived from font size
re-fit around the bigger text automatically.

server/app/calendar_render.py

@@ -512,10 +512,12 @@ _AGENDA_FONTS = {"large": (34, 22, 20), "medium": (24, 22, 16), "small": (18, 16
 
 def _build_agenda(events: list[dict], browse_offset: int, target_w: int, target_h: int, tz: ZoneInfo,
                   palette_rgb: list | None = None, weather_cities: list[dict] | None = None,
-                  weather_units: str = "fahrenheit") -> Image.Image:
+                  weather_units: str = "fahrenheit", font_scale: float = 1.0) -> Image.Image:
     img, draw, region = panel_style.card_canvas(target_w, target_h)
 
-    title_size, body_size, weather_size = _AGENDA_FONTS[_size_tier(target_w, target_h)]
+    title_size, body_size, weather_size = (
+        panel_style.scaled_size(v, font_scale) for v in _AGENDA_FONTS[_size_tier(target_w, target_h)]
+    )
     title_font = panel_style.font_bold(title_size)
     body_font = panel_style.font_regular(body_size)
     weather_font = panel_style.font_regular(weather_size)
@@ -533,7 +535,7 @@ _TODAY_TOMORROW_FONTS = {"large": (26, 18, 16), "medium": (20, 15, 13), "small":
 
 def _build_today_tomorrow(events: list[dict], browse_offset: int, target_w: int, target_h: int, tz: ZoneInfo,
                           palette_rgb: list | None = None, weather_cities: list[dict] | None = None,
-                          weather_units: str = "fahrenheit") -> Image.Image:
+                          weather_units: str = "fahrenheit", font_scale: float = 1.0) -> Image.Image:
     """Two _draw_agenda_day sections stacked vertically (below each other
     rather than side-by-side -- narrower than tall doesn't leave enough
     width per day for the event-row text at smaller sizes). browse_offset
@@ -542,7 +544,9 @@ def _build_today_tomorrow(events: list[dict], browse_offset: int, target_w: int,
     both views."""
     img, draw, (cx0, cy0, cw, ch) = panel_style.card_canvas(target_w, target_h)
 
-    title_size, body_size, weather_size = _TODAY_TOMORROW_FONTS[_size_tier(target_w, target_h)]
+    title_size, body_size, weather_size = (
+        panel_style.scaled_size(v, font_scale) for v in _TODAY_TOMORROW_FONTS[_size_tier(target_w, target_h)]
+    )
     title_font = panel_style.font_bold(title_size)
     body_font = panel_style.font_regular(body_size)
     weather_font = panel_style.font_regular(weather_size)
@@ -572,7 +576,7 @@ def _build_week(events: list[dict], browse_offset: int, target_w: int, target_h:
                 week_start: int, palette_rgb: list | None = None,
                 weather_cities: list[dict] | None = None, weather_units: str = "fahrenheit",
                 days: int = 7, layout: str = "horizontal",
-                start_offset: int = 0) -> Image.Image:
+                start_offset: int = 0, font_scale: float = 1.0) -> Image.Image:
     """`days` (2-10, see routers/api_widgets.py's clamp) side-by-side
     columns (layout="horizontal", the original fixed-at-7 behavior
     generalized) or stacked bands (layout="vertical", reusing
@@ -597,9 +601,9 @@ def _build_week(events: list[dict], browse_offset: int, target_w: int, target_h:
 
     if layout == "vertical":
         title_base, body_base, weather_base = _WEEK_VERTICAL_FONTS[tier]
-        title_font = panel_style.font_bold(max(14, title_base - days))
-        body_font = panel_style.font_regular(max(11, body_base - days))
-        weather_font = panel_style.font_regular(max(9, weather_base - days))
+        title_font = panel_style.font_bold(panel_style.scaled_size(max(14, title_base - days), font_scale))
+        body_font = panel_style.font_regular(panel_style.scaled_size(max(11, body_base - days), font_scale))
+        weather_font = panel_style.font_regular(panel_style.scaled_size(max(9, weather_base - days), font_scale))
         section_h = ch // days
         for i in range(days):
             section_y0 = cy0 + i * section_h
@@ -611,7 +615,9 @@ def _build_week(events: list[dict], browse_offset: int, target_w: int, target_h:
                              weather_cities, weather_font, weather_units)
         return img
 
-    header_size, chip_size, weather_size = _WEEK_HORIZONTAL_FONTS[tier]
+    header_size, chip_size, weather_size = (
+        panel_style.scaled_size(v, font_scale) for v in _WEEK_HORIZONTAL_FONTS[tier]
+    )
     header_font = panel_style.font_bold(header_size)
     chip_font = panel_style.font_regular(chip_size)
     weather_font = panel_style.font_regular(weather_size)
@@ -667,7 +673,7 @@ _MONTH_FONTS = {"large": (16, 18), "medium": (12, 13), "small": (12, 13)}
 
 
 def _build_month(events: list[dict], browse_offset: int, target_w: int, target_h: int, tz: ZoneInfo,
-                 week_start: int, palette_rgb: list | None = None) -> Image.Image:
+                 week_start: int, palette_rgb: list | None = None, font_scale: float = 1.0) -> Image.Image:
     """Density dots per day, not literal event text -- real text at
     typical month-cell size (~100x70px) is close to unreadable on a
     6-color dithered e-ink panel. Capped at 4 visible dots, "+N" beyond.
@@ -677,7 +683,9 @@ def _build_month(events: list[dict], browse_offset: int, target_w: int, target_h
     comment above MARGIN/BG/FG."""
     img, draw, (cx0, cy0, cw, ch) = panel_style.card_canvas(target_w, target_h)
 
-    header_size, day_size = _MONTH_FONTS[_size_tier(target_w, target_h)]
+    header_size, day_size = (
+        panel_style.scaled_size(v, font_scale) for v in _MONTH_FONTS[_size_tier(target_w, target_h)]
+    )
     header_font = panel_style.font_bold(header_size)
     day_font_in_month = panel_style.font_bold(day_size)
     day_font_out_of_month = panel_style.font_regular(day_size)
@@ -750,7 +758,7 @@ def _build(events: list[dict], view: str, browse_offset: int, target_w: int, tar
           fetch_summary: str, week_start: int, palette_rgb: list | None = None,
           weather_cities: list[dict] | None = None, weather_units: str = "fahrenheit",
           week_days: int = 7, week_layout: str = "horizontal",
-          week_start_offset: int = 0) -> Image.Image:
+          week_start_offset: int = 0, font_scale: float = 1.0) -> Image.Image:
     tz = ZoneInfo(timezone) if timezone else ZoneInfo("UTC")
     effective_view = view
     if view == "month" and not _month_view_fits(target_w, target_h):
@@ -758,13 +766,13 @@ def _build(events: list[dict], view: str, browse_offset: int, target_w: int, tar
 
     if effective_view == "agenda":
         img = _build_agenda(events, browse_offset, target_w, target_h, tz, palette_rgb,
-                            weather_cities, weather_units)
+                            weather_cities, weather_units, font_scale)
     elif effective_view == "today_tomorrow":
         img = _build_today_tomorrow(events, browse_offset, target_w, target_h, tz, palette_rgb,
-                                    weather_cities, weather_units)
+                                    weather_cities, weather_units, font_scale)
     elif effective_view == "week":
         img = _build_week(events, browse_offset, target_w, target_h, tz, week_start, palette_rgb,
-                          weather_cities, weather_units, week_days, week_layout, week_start_offset)
+                          weather_cities, weather_units, week_days, week_layout, week_start_offset, font_scale)
     elif effective_view == "month":
         # Never given weather -- no room for it at typical month-cell
         # size, same reasoning that already keeps this view to density
@@ -772,10 +780,10 @@ def _build(events: list[dict], view: str, browse_offset: int, target_w: int, tar
         # docstring). Colors are still passed through, though -- that's
         # a different concern (legibility of individual events) than
         # needing a whole extra strip of content.
-        img = _build_month(events, browse_offset, target_w, target_h, tz, week_start, palette_rgb)
+        img = _build_month(events, browse_offset, target_w, target_h, tz, week_start, palette_rgb, font_scale)
     else:
         img = _build_agenda(events, browse_offset, target_w, target_h, tz, palette_rgb,
-                            weather_cities, weather_units)
+                            weather_cities, weather_units, font_scale)
 
     if fetch_summary:
         # Drawn as a final overlay onto the already-composited img (not
@@ -814,13 +822,13 @@ def render_calendar_preview_png(events: list[dict], view: str, browse_offset: in
                                 fetch_summary: str = "", manage: dict | None = None, week_start: int = 0,
                                 weather_cities: list[dict] | None = None, weather_units: str = "fahrenheit",
                                 week_days: int = 7, week_layout: str = "horizontal",
-                                week_start_offset: int = 0) -> bytes:
+                                week_start_offset: int = 0, font_scale: float = 1.0) -> bytes:
     """Same pipeline as render_calendar, but a normal browser-viewable
     PNG in logical (upright) orientation -- mirrors
     image_pipeline.render_preview_png's relationship to render_frame."""
     target_w, target_h = logical_render_size(orientation)
     img = _build(events, view, browse_offset, target_w, target_h, timezone, fetch_summary, week_start,
-                palette_rgb, weather_cities, weather_units, week_days, week_layout, week_start_offset)
+                palette_rgb, weather_cities, weather_units, week_days, week_layout, week_start_offset, font_scale)
     img = _apply_manage_overlay(img, manage)
     quantized = _quantize(img, palette_rgb, dither_strength=1.0)
     buf = io.BytesIO()
@@ -835,12 +843,14 @@ _TASKS_FONTS = {"large": (24, 18), "medium": (20, 16), "small": (16, 13)}
 
 
 def _build_tasks(tasks: list[dict], target_w: int, target_h: int, palette_rgb: list | None = None,
-                 title: str = "Tasks") -> Image.Image:
+                 title: str = "Tasks", font_scale: float = 1.0) -> Image.Image:
     """A tasks widget's entire region is the checklist -- unlike the old
     week-view slot, there's no day columns/header to share space with,
     so this is just _draw_tasks over the whole box."""
     img, draw, region = panel_style.card_canvas(target_w, target_h)
-    title_size, body_size = _TASKS_FONTS[_size_tier(target_w, target_h)]
+    title_size, body_size = (
+        panel_style.scaled_size(v, font_scale) for v in _TASKS_FONTS[_size_tier(target_w, target_h)]
+    )
     title_font = panel_style.font_bold(title_size)
     body_font = panel_style.font_regular(body_size)
     _draw_tasks(img, draw, region, tasks, title_font, body_font, palette_rgb, title)
@@ -860,12 +870,12 @@ def render_tasks(tasks: list[dict], orientation: str, palette_rgb: list | None,
 
 
 def render_tasks_preview_png(tasks: list[dict], orientation: str, palette_rgb: list | None,
-                             manage: dict | None = None, title: str = "Tasks") -> bytes:
+                             manage: dict | None = None, title: str = "Tasks", font_scale: float = 1.0) -> bytes:
     """Same pipeline as render_tasks, but a normal browser-viewable PNG
     in logical (upright) orientation -- mirrors render_calendar_preview_
     png's relationship to render_calendar."""
     target_w, target_h = logical_render_size(orientation)
-    img = _build_tasks(tasks, target_w, target_h, palette_rgb, title)
+    img = _build_tasks(tasks, target_w, target_h, palette_rgb, title, font_scale=font_scale)
     img = _apply_manage_overlay(img, manage)
     quantized = _quantize(img, palette_rgb, dither_strength=1.0)
     buf = io.BytesIO()