Enable Open Weather as a source for the DE / DX Weather panels

[w8be]

Since Open Weather support is already developed for cloud layers, it would be nice to just use it as the source for the weather data fetches.

[accius]

Built, ships next release: Settings → Profiles now has a Weather Source picker — Open-Meteo stays the keyless default, and OpenWeatherMap is selectable with your own free-tier key (stored in your browser only, like the other credentials). It maps OWM's current + 3-hourly forecast into the same shape the panels already use, so DE/DX weather, forecasts and all just work. One honest caveat: OWM's free tier has no UV index. 73, K0CJH