Radar flyout now also shows a 3-day Open-Meteo forecast (free, no API
key) for the map's current center. Radar frames and the forecast fetch
independently — one being unreachable doesn't hide the other. The last
successful forecast is cached in localStorage and shown (with a
"cached from" note) when the live fetch fails, so there's still
something useful once actually offline.
Radar tile images themselves aren't cached — that needs a Service
Worker, left as a separate follow-up (see TODO.adoc).
randy
8d090b0774