fix(weather): match prep behavior — serve cached weather regardless of age

The /api/journal/weather route was filtering out cache rows older than 24
hours via parse_weather_card_data, while journal_prep.py read the same
rows raw without freshness checking. Result: the daily prep referenced
"home" and "work" temperatures while the right-rail UI showed nothing —
two surfaces, same backing data, inconsistent visibility.

Two changes:

1. parse_weather_card_data no longer returns None for stale data.
   WeatherCard already exposes fetched_at and gracefully hides
   today_high / forecast fields when they're absent, so old data renders
   with whatever fields the cached forecast still covers.

2. The /weather route opportunistically schedules a background refresh
   for any cache row older than 4 hours. If the user's journal_config
   has lat/lon for that location_key, the refresh runs and the next
   page load gets fresh data; if no usable config, the refresh is a
   silent no-op and the stale cache is still served.

This makes prep and UI consistent. It also self-heals over time — once
locations are configured, stale caches get refreshed on the next page
load instead of waiting indefinitely.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/fabledassistant/services/weather.py

@@ -156,15 +156,13 @@ def parse_weather_card_data(
 ) -> dict | None:
     """
     Parse a WeatherCache row into the metadata.weather card schema.
-    Returns None if the cache is stale (older than 24 hours) or unavailable.
+    Returns None if the cache row is missing or unparseable. Stale data is
+    returned as-is — the frontend uses `fetched_at` to convey freshness, and
+    WeatherCard handles missing today/forecast fields gracefully.
     """
     from datetime import date, timedelta
 
-    if cache_row is None or cache_row.fetched_at is None:
-        return None
-
-    age_seconds = (datetime.now(timezone.utc) - cache_row.fetched_at).total_seconds()
-    if age_seconds > 86400:
+    if cache_row is None or cache_row.fetched_at is None or not cache_row.forecast_json:
         return None
 
     raw = cache_row.forecast_json or {}