Add standalone weather widget (current/hourly/daily/multi-city, pluggable providers)

New widget type with four display modes -- current conditions, an
hourly forecast strip, a multi-day forecast, and several cities' current
day side by side -- backed by a pluggable provider registry (app/weather/,
mirroring the app/widgets/ dispatch pattern): Open-Meteo (worldwide) and
NWS (US-only) both wired up now, Environment Canada documented as the
next one to add given its more involved station/grid-lookup API.

The calendar widget's existing embedded weather strip is untouched and
still Open-Meteo-only; this lifts the same underlying icon-drawing
primitives (now shared via app/weather_render.py, calendar_render.py
still imports draw_weather_row unchanged) into a widget that can be
placed and sized on its own. Icons are redrawn in the panel's actual ink
colors (yellow sun/bolt, blue rain/snow) instead of flat black, and
build_multi_city's icon/font sizing now scales with how many cities need
to fit rather than the box's height alone -- both fixed after catching
them via live browser verification, along with a mode-switch cache-shape
crash and a mobile-width dialog overflow.

New WeatherWidgetConfig table (migration 24), grid footprint, widget
module, common.py fetch/cache helper, router endpoints (location set/
clear, city add/remove, preview), dialog template + JS, and full test
coverage (providers, widget render, HTTP endpoints, migration replay).
docs/widgets.md and CLAUDE.md's TODO updated accordingly.

server/app/models.py

@@ -433,7 +433,7 @@ class Widget(Base):
 
     id: Mapped[int] = mapped_column(primary_key=True)
     frame_id: Mapped[int] = mapped_column(ForeignKey("frames.id", ondelete="CASCADE"))
-    widget_type: Mapped[str] = mapped_column(String)  # "photos" | "calendar" | "whiteboard" | "tasks"
+    widget_type: Mapped[str] = mapped_column(String)  # "photos" | "calendar" | "whiteboard" | "tasks" | "static" | "text" | "weather"
     x: Mapped[int] = mapped_column(Integer)
     y: Mapped[int] = mapped_column(Integer)
     w: Mapped[int] = mapped_column(Integer)
@@ -553,6 +553,41 @@ class WhiteboardWidgetConfig(Base):
     cached_image: Mapped[bytes | None] = mapped_column(LargeBinary, nullable=True)
 
 
+class WeatherWidgetConfig(Base):
+    """One weather widget's settings + cached-fetch state. Four display
+    modes (see app/widgets/weather.py): "current" (one city, current
+    temp + icon), "hourly" (one city, a row of ticks across the day),
+    "daily" (one city, a multi-day strip), "multi_city" (several cities'
+    current-day high/low/icon side by side -- the calendar widget's
+    embedded weather strip, lifted out into its own widget type).
+    `provider` selects which of app/weather/'s PROVIDERS actually fetches
+    ("open_meteo" | "nws" -- see that package's own module docstring).
+    `cached`'s shape depends on `mode`: {"temp","category"} for current,
+    a list of {"time","temp","category"} for hourly, a
+    {"YYYY-MM-DD": {...}} dict for daily, or a list of
+    {"label","high","low","category"} for multi_city."""
+
+    __tablename__ = "weather_widget_configs"
+
+    widget_id: Mapped[int] = mapped_column(ForeignKey("widgets.id", ondelete="CASCADE"), primary_key=True)
+    mode: Mapped[str] = mapped_column(String, default="current")  # current | hourly | daily | multi_city
+    provider: Mapped[str] = mapped_column(String, default="open_meteo")  # open_meteo | nws
+    units: Mapped[str] = mapped_column(String, default="fahrenheit")  # fahrenheit | celsius
+    # Single-location modes only (current/hourly/daily) -- geocoded once
+    # via weather.geocode_city() when set, same idiom as
+    # CalendarWidgetConfig.weather_cities' per-entry shape.
+    city_label: Mapped[str | None] = mapped_column(String, nullable=True)
+    city_latitude: Mapped[float | None] = mapped_column(Float, nullable=True)
+    city_longitude: Mapped[float | None] = mapped_column(Float, nullable=True)
+    hourly_interval_hours: Mapped[int] = mapped_column(Integer, default=4)
+    daily_days: Mapped[int] = mapped_column(Integer, default=5)
+    # multi_city mode only -- [{"label", "latitude", "longitude"}, ...],
+    # same shape as CalendarWidgetConfig.weather_cities.
+    cities: Mapped[list | None] = mapped_column(JSON, nullable=True, default=None)
+    checked_at: Mapped[float] = mapped_column(Float, default=0.0)
+    cached: Mapped[dict | list | None] = mapped_column(JSON, nullable=True, default=None)
+
+
 class TextWidgetConfig(Base):
     """One text widget's authored content + display settings -- another
     no-live-upstream type like StaticWidgetConfig, just parsed rich text
@@ -618,6 +653,7 @@ WIDGET_CONFIG_MODELS: dict[str, type] = {
     "tasks": TaskWidgetConfig,
     "static": StaticWidgetConfig,
     "text": TextWidgetConfig,
+    "weather": WeatherWidgetConfig,
 }