Add a text widget (rich text: bold/italic/underline, per-run color/highlight)

A new self-contained widget type showing user-authored rich text -- no
live upstream to poll, like the static image widget, just word-wrapped
styled text instead of an uploaded image.

The dialog's contenteditable HTML is never stored or replayed as HTML:
app/text_content.py parses it server-side (on save) into a plain
paragraphs-of-styled-runs structure -- the actual sanitization
boundary, since raw HTML never round-trips back into any browser DOM
(the dialog rebuilds its editor from that same JSON via
createElement/textContent). app/widgets/text.py renders it with a
custom word-wrap/shrink-to-fit layout, using real vendored font weights
(app/fonts/NotoSans-{Regular,Bold,Italic,BoldItalic}.ttf, OFL-licensed
like the emoji fonts already there) rather than every other widget's
single ImageFont.load_default() -- the one widget type where that
distinction matters.

server/app/routers/api_widgets.py

@@ -33,6 +33,7 @@ from ..image_pipeline import (
     DEFAULT_DISPLAY_MODE,
     DEFAULT_STATIC_DISPLAY_MODE,
     DISPLAY_MODES,
+    hex_to_rgb,
     STATIC_DISPLAY_MODES,
     render_preview_png,
 )
@@ -45,11 +46,14 @@ from ..models import (
     PhotoWidgetConfig,
     StaticWidgetConfig,
     TaskWidgetConfig,
+    TextWidgetConfig,
     WhiteboardWidgetConfig,
     WIDGET_CONFIG_MODELS,
     Widget,
 )
+from ..text_content import has_text, parse_rich_text
 from ..widgets import WIDGET_TYPES
+from ..widgets import text as text_widget
 from .common import (
     calendar_sources_for_widget,
     fetch_source_and_faces,
@@ -69,6 +73,8 @@ router = APIRouter()
 
 MIN_QUEUE_TARGET_LEN = 5
 MAX_QUEUE_TARGET_LEN = 5000
+MIN_TEXT_FONT_SIZE = 10
+MAX_TEXT_FONT_SIZE = 96
 CALENDAR_COLOR_INDEX_RANGE = range(2, 6)  # Yellow/Red/Blue/Green -- see PALETTE_LABELS
 MAX_TASKS_NAME_LEN = 40  # a sane on-panel-header length, see calendar_render._draw_tasks
 
@@ -271,6 +277,11 @@ def api_widget_config_save(
     # tasks
     tasks_name: str | None = Form(None),
     tasks_show_completed: bool | None = Form(None),
+    # text
+    text_html: str | None = Form(None),
+    text_font_size: int | None = Form(None),
+    text_align: str | None = Form(None),
+    text_background_color: str | None = Form(None),
 ):
     """Every field optional -- same partial-update, form-urlencoded
     convention as the old frame-level api_config_save, now scoped to one
@@ -347,6 +358,21 @@ def api_widget_config_save(
         with widget_locked(db, frame.id, widget.id) as (_, _, scfg):
             if display_mode is not None:
                 scfg.display_mode = display_mode if display_mode in STATIC_DISPLAY_MODES else DEFAULT_STATIC_DISPLAY_MODE
+    elif widget.widget_type == "text":
+        with widget_locked(db, frame.id, widget.id) as (_, _, xcfg):
+            if text_html is not None:
+                # The one save path that touches app/text_content.py --
+                # see its module docstring for why parsing (not storing
+                # raw HTML) is the actual sanitization boundary here.
+                xcfg.content = parse_rich_text(text_html)
+            if text_font_size is not None:
+                xcfg.font_size = max(MIN_TEXT_FONT_SIZE, min(MAX_TEXT_FONT_SIZE, text_font_size))
+            if text_align is not None:
+                xcfg.align = text_align if text_align in ("left", "center", "right") else "left"
+            if text_background_color is not None:
+                xcfg.background_color = (
+                    text_background_color if hex_to_rgb(text_background_color) else "#ffffff"
+                )
     with frame_locked(db, frame.id) as cfg:
         cfg.stats_config_saves += 1
     return {"status": "saved"}
@@ -852,6 +878,25 @@ def api_widget_preview_static(
     return Response(content=png, media_type="image/png")
 
 
+# --- Text: preview ----------------------------------------------------------
+
+@router.get("/api/frames/{frame_id}/widgets/{widget_id}/preview/text")
+def api_widget_preview_text(
+    frame_widget: tuple[Frame, Widget] = Depends(require_widget_view), db: Session = Depends(get_db)
+):
+    """The saved rich text run through the same word-wrap/shrink-to-fit
+    layout and quantize pass a live device render would use -- same
+    "reflects what's currently saved" convention as the other preview
+    endpoints."""
+    frame, widget = frame_widget
+    _require_widget_type(widget, "text")
+    xcfg = db.get(TextWidgetConfig, widget.id)
+    if not has_text(xcfg.content):
+        raise HTTPException(400, "No text authored on this widget yet")
+    png = text_widget.render_preview_png(xcfg, orientation=frame.orientation, palette_rgb=frame.palette_rgb)
+    return Response(content=png, media_type="image/png")
+
+
 # --- Whiteboard: source/preview ------------------------------------------
 
 class WhiteboardSourceRequest(BaseModel):

server/app/routers/frame_pages.py

@@ -35,6 +35,7 @@ from ..models import (
     PhotoWidgetConfig,
     StaticWidgetConfig,
     TaskWidgetConfig,
+    TextWidgetConfig,
     User,
     UserFrame,
     WhiteboardWidgetConfig,
@@ -245,6 +246,12 @@ def widget_dialog(frame_id: int, widget_id: int, request: Request, db: Session =
             "display_mode_labels": {k: v for k, v in DISPLAY_MODE_LABELS.items() if k in STATIC_DISPLAY_MODES},
         })
 
+    if widget.widget_type == "text":
+        text_cfg = db.get(TextWidgetConfig, widget.id)
+        return templates.TemplateResponse("_widget_dialog_text.html", {
+            "request": request, "frame": frame, "widget": widget, "text_cfg": text_cfg,
+        })
+
     if widget.widget_type == "whiteboard":
         whiteboard_cfg = db.get(WhiteboardWidgetConfig, widget.id)
         viewer_has_webdav_creds = bool(