fix: cache open-meteo and timezone requests for offline use

[aeharding]

Going offline loaded the app shell but no forecast data.

The offline cache is the Workbox runtime-caching config, which matches by URL prefix. Winds aloft used to be fetched from /api/rap, covered by a 4-hour NetworkFirst rule. b9d12e6 removed rucsoundings support and deleted that rule, but the replacement source (Open-Meteo, at /api/openmeteo/forecast) never had one.

That made the failure total rather than partial: getWeather awaits loadWindsAloft() before anything else, so when that request throws offline the thunk rejects and alerts, TAF, and the NWS forecast never load — even though those endpoints were still cached.

• Add /api/openmeteo.* → NetworkFirst, 4 hours, matching the other weather caches. Covers both the winds-aloft and hourly-weather calls.
• Add /api/timezone.* → NetworkFirst, 7 days. Also uncached; outside the US it is the only timezone source, so offline fell back to "using local time".
• Drop a duplicate /api/weather rule — two identical entries existed and the second was unreachable.

Verified with a fresh pnpm build: the generated service-worker.js registers apiOpenMeteoCache and apiTimezoneCache, with a single apiWeatherCache route.

Note: this only takes effect once the new service worker activates and the app is loaded online once to populate the cache.