Add weather to calendar mode; fix CalDAV events never showing

Weather: multiple cities per frame, geocoded via Open-Meteo (no API
key), shown above the event list on agenda/today & tomorrow/week views
-- never month, no room for it there. Hand-drawn sun/cloud/rain/snow/
thunderstorm icons (no new font/icon asset, same primitives-only
approach the rest of calendar_render.py already uses). City geocoding
handles "City, State" qualifiers Open-Meteo's own search doesn't
(disambiguates same-named cities, e.g. the three "Portland"s).

CalDAV fix: events were never showing despite calendars discovering
fine, because fetch_calendar_events relied on the calendar-query
REPORT's server-side time-range filter, which real servers implement
inconsistently (confirmed against a real server, not just guessed --
reproduced locally with Radicale). Switched to fetching every event
unfiltered and doing all date-window filtering/expansion client-side,
same approach already used for plain ICS feeds.

server/app/migration.py

@@ -145,6 +145,21 @@ def _migration_9(conn) -> None:
     conn.execute(text("ALTER TABLE user_frames DROP COLUMN calendar_included"))
 
 
+def _migration_10(conn) -> None:
+    """Optional weather strip for calendar mode (agenda/today & tomorrow/
+    week views -- never month, see calendar_render.py's _BUILDERS).
+    Multiple cities per frame (calendar_weather_cities), each geocoded
+    once via weather.py's Open-Meteo lookup (no API key) and their daily
+    forecasts refreshed on their own throttle, same shape idiom as
+    calendar_checked_at/calendar_cached_events. Off by default -- no
+    existing frame's render changes until its Calendar tab turns it on."""
+    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_weather_enabled INTEGER NOT NULL DEFAULT 0"))
+    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_weather_units TEXT NOT NULL DEFAULT 'fahrenheit'"))
+    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_weather_cities TEXT"))
+    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_weather_checked_at REAL NOT NULL DEFAULT 0.0"))
+    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_weather_cached TEXT"))
+
+
 MIGRATIONS = [
     (1, _migration_1),
     (2, _migration_2),
@@ -155,6 +170,7 @@ MIGRATIONS = [
     (7, _migration_7),
     (8, _migration_8),
     (9, _migration_9),
+    (10, _migration_10),
 ]