Location-aware live weather background + location…

Details

Make the ambient background reflect the real current weather at the
visitor's location (default New York City) instead of a date-derived
season, and add a dropdown to change the location.
- weather-service.ts: resolve + persist the active location, fetch the
  current conditions from Open-Meteo (keyless, CORS), map WMO codes to a
  scene kind + intensity, derive day/night from the location's own local
  time, geocode city searches, and fall back to a season-derived scene
  when offline. Publishes a `wxdata` event.
- seasonal-background.ts: weather-driven scene selection (clear day,
  clear night, clouds, fog, drizzle, rain, thunder, snow, sleet) with
  drifting clouds, twinkling stars, a moon, lightning and a night wash.
  Keeps the physics engine and the legacy season fallback (v2/offline).
- snow-gl.ts: GPU snow now activates on snow/sleet (lazy WebGL init),
  with a season fallback when the weather service is absent (v2).
- weather-location-picker.ts + v3 markup/SCSS: a glass popover with live
  conditions, a city search and preset chips; choosing a city switches
  the weather and enables the visual.
Weather stays off by default; ?weather= / ?season= still preview scenes.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Mn7fa3Z4bpbSAj4edBnjXA

Files changed (9)