feat(weather): migrate /api/weather to the NestJS pilot module (L1) (#1053)

First strangler migration (L1): /api/weather is served by a NestJS module.

- @trek/shared/weather Zod contract; Nest controller byte-identical to the legacy Express route (paths, query params, status codes, { error } bodies, lang default, ApiError/500 passthrough). Service reuses getWeather/getDetailedWeather (+ shared cache; MCP tools unchanged).
- Strangler routes /api/weather to Nest by default; the legacy Express route + its migration-time parity test were decommissioned in this PR.
- Frontend (FE2): weatherApi typed against the @trek/shared WeatherResult contract.
- Harness: reusable Nest-vs-Express parity harness, e2e harness (temp SQLite + seed/cookie helpers, real JwtAuthGuard), src/nest coverage gate raised to >=80%, src/nest test guide.
- Verified end-to-end on a prod mirror (dev1): 401/400/200 via Nest with real Open-Meteo data, Express route gone.

server/src/app.ts

@@ -26,7 +26,6 @@ import airportsRoutes from './routes/airports';
 import filesRoutes from './routes/files';
 import reservationsRoutes from './routes/reservations';
 import dayNotesRoutes from './routes/dayNotes';
-import weatherRoutes from './routes/weather';
 import settingsRoutes from './routes/settings';
 import budgetRoutes from './routes/budget';
 import collabRoutes from './routes/collab';
@@ -361,7 +360,8 @@ export function createApp(): express.Application {
   app.use('/api/photos', photoRoutes);
   app.use('/api/maps', mapsRoutes);
   app.use('/api/airports', airportsRoutes);
-  app.use('/api/weather', weatherRoutes);
+  // /api/weather is served by the NestJS weather module (see src/nest/weather);
+  // the legacy Express route was decommissioned after the migration (L1).
   app.use('/api/settings', settingsRoutes);
   app.use('/api/system-notices', systemNoticesRoutes);
   app.use('/api/backup', backupRoutes);