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/routes/journal.py

@@ -8,6 +8,7 @@ The ambient endpoints read locations + temp_unit + topic preferences from the
 """
 from __future__ import annotations
 
+import asyncio
 import datetime
 import json
 import logging
@@ -222,12 +223,50 @@ async def _journal_temp_unit(user_id: int) -> str:
 # ── Weather ───────────────────────────────────────────────────────────────────
 
 
+_STALE_THRESHOLD_SECONDS = 4 * 3600  # 4 hours — start refreshing well before the 7-day forecast window slides past today
+
+
+def _is_stale(cache_row) -> bool:
+    if cache_row is None or cache_row.fetched_at is None:
+        return True
+    age = (datetime.datetime.now(datetime.timezone.utc) - cache_row.fetched_at).total_seconds()
+    return age > _STALE_THRESHOLD_SECONDS
+
+
+async def _refresh_stale_in_background(user_id: int, stale_keys: set[str]) -> None:
+    """Best-effort refresh of stale cache rows. Silently no-ops if the user's
+    config has no usable lat/lon for a given location_key."""
+    cfg = await _resolve_config(user_id)
+    locations = cfg.get("locations") or {}
+    for key in stale_keys:
+        loc = locations.get(key)
+        if not loc or not loc.get("lat") or not loc.get("lon"):
+            continue
+        try:
+            await weather_svc.refresh_location_cache(
+                user_id=user_id,
+                location_key=key,
+                location_label=loc.get("label", key),
+                lat=loc["lat"],
+                lon=loc["lon"],
+            )
+        except Exception:
+            logger.warning("Background weather refresh failed for user %d / %s", user_id, key, exc_info=True)
+
+
 @journal_bp.get("/weather")
 @login_required
 async def get_weather():
     user_id = get_current_user_id()
     rows = await weather_svc.get_cached_weather_rows(user_id)
     temp_unit = await _journal_temp_unit(user_id)
+
+    # Kick off a best-effort background refresh for stale rows so the next page
+    # load gets fresh data; we still serve whatever's currently cached now.
+    stale_keys = {row.location_key for row in rows if _is_stale(row)}
+    if stale_keys:
+        asyncio.create_task(_refresh_stale_in_background(user_id, stale_keys))
+
     cards = [
         card for row in rows
         if (card := weather_svc.parse_weather_card_data(row, temp_unit)) is not None