Adds ALLOWED_WEATHER_METRICS frozenset and 5 new query functions:
- get_weather_locations(): 12 locations with latest stress index for map/cards
- get_weather_location_series(): time series for one location (dynamic metrics)
- get_weather_stress_latest(): global snapshot for Pulse metric card
- get_weather_stress_trend(): daily global avg/max for chart and sparkline
- get_weather_active_alerts(): locations with active stress flags
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>