Add TFR warning banner for airspace restrictions

Fetches active Temporary Flight Restrictions from the FAA website,
filters by configured state (LOCATION_STATE env var), and displays
a red warning banner at the top of the dashboard when TFRs are present.
Data is cached for 30 minutes and degrades gracefully if the FAA is unreachable.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/hooks/use-weather.ts

@@ -1,8 +1,8 @@
 'use client'
 
 import { useQuery } from '@tanstack/react-query'
-import { getCurrentWeather, getForecast, getHistorical } from '@/lib/api'
-import type { CurrentWeatherResponse, ForecastResponse, HistoricalResponse } from '@/lib/types'
+import { getCurrentWeather, getForecast, getHistorical, getTfrs } from '@/lib/api'
+import type { CurrentWeatherResponse, ForecastResponse, HistoricalResponse, TFRResponse } from '@/lib/types'
 
 const STALE_TIME = 5 * 60 * 1000 // 5 minutes
 const REFETCH_INTERVAL = 5 * 60 * 1000 // 5 minutes
@@ -35,3 +35,15 @@ export function useHistorical(date: string, lat?: number, lon?: number) {
     enabled: !!date,
   })
 }
+
+const TFR_STALE_TIME = 30 * 60 * 1000 // 30 minutes
+const TFR_REFETCH_INTERVAL = 30 * 60 * 1000 // 30 minutes
+
+export function useTfrs() {
+  return useQuery<TFRResponse>({
+    queryKey: ['airspace', 'tfrs'],
+    queryFn: () => getTfrs(),
+    staleTime: TFR_STALE_TIME,
+    refetchInterval: TFR_REFETCH_INTERVAL,
+  })
+}