feat(wetter): add weather module with Open-Meteo, DWD alerts, and rain nowcast

New module providing weather data for the DACH region via three sources:
- Open-Meteo (DWD ICON-D2 model) for current conditions and 7-day forecast
- DWD warnings endpoint for severe weather alerts
- Rainbow.ai / Open-Meteo fallback for minute-level rain nowcast

Includes API proxy with in-memory caching, Svelte 5 UI with location
picker, hourly/daily forecast, alert cards, and precipitation bar chart.
Two AI tools (get_weather, get_rain_forecast) enable the companion to
answer weather questions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/api/src/index.ts

@@ -38,6 +38,7 @@ import { tracesRoutes } from './modules/traces/routes';
 import { presiRoutes } from './modules/presi/routes';
 import { researchRoutes } from './modules/research/routes';
 import { whoRoutes } from './modules/who/routes';
+import { wetterRoutes } from './modules/wetter/routes';
 
 const PORT = parseInt(process.env.PORT || '3060', 10);
 const CORS_ORIGINS = (process.env.CORS_ORIGINS || 'http://localhost:5173').split(',');
@@ -75,6 +76,7 @@ app.route('/api/v1/traces', tracesRoutes);
 app.route('/api/v1/presi', presiRoutes);
 app.route('/api/v1/research', researchRoutes);
 app.route('/api/v1/who', whoRoutes);
+app.route('/api/v1/wetter', wetterRoutes);
 
 // ─── Server Info ────────────────────────────────────────────
 console.log(`mana-api starting on port ${PORT}...`);