feat(weather): OWM-Fallback über Server-.env wenn kein User-Key

Wetter-Proxy auf /api/weather/current nutzt optionalen Nutzer-Key aus
den Einstellungen, sonst OpenWeatherMapAPIKey aus der Umgebung.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/src/services/weather.ts

@@ -0,0 +1,52 @@
+export class WeatherApiError extends Error {
+  code: 'NO_KEY' | 'REQUEST_FAILED'
+
+  constructor(message: string, code: 'NO_KEY' | 'REQUEST_FAILED' = 'REQUEST_FAILED') {
+    super(message)
+    this.name = 'WeatherApiError'
+    this.code = code
+  }
+}
+
+function buildWeatherHeaders(): Record<string, string> {
+  const headers: Record<string, string> = {}
+  const userId = localStorage.getItem('active_userid')
+  const userKey = localStorage.getItem('owm_api_key')?.trim()
+
+  if (userId) headers['X-User-Id'] = userId
+  if (userKey) headers['X-OWM-Api-Key'] = userKey
+
+  return headers
+}
+
+export async function fetchOpenWeatherCurrent(params: {
+  lat?: string
+  lon?: string
+  q?: string
+}): Promise<Record<string, unknown>> {
+  const searchParams = new URLSearchParams()
+
+  if (params.lat && params.lon) {
+    searchParams.set('lat', params.lat)
+    searchParams.set('lon', params.lon)
+  } else if (params.q?.trim()) {
+    searchParams.set('q', params.q.trim())
+  } else {
+    throw new WeatherApiError('lat/lon or location query required')
+  }
+
+  const res = await fetch(`/api/weather/current?${searchParams.toString()}`, {
+    headers: buildWeatherHeaders()
+  })
+
+  if (res.status === 503) {
+    throw new WeatherApiError('No OpenWeatherMap API key configured', 'NO_KEY')
+  }
+
+  const data = await res.json()
+  if (!res.ok) {
+    throw new WeatherApiError('Weather API rejected the request')
+  }
+
+  return data
+}