Opening the view offline still requests every feed #460

Opening the PodNotes view while offline still sends a feed request for every subscribed podcast.

Reproduce (found while verifying #459; evidence in the V-459 verifier report)

1. Subscribe to several public feeds and let the feed cache expire.
2. Close the PodNotes view, go offline (navigator.onLine false, feed server unreachable), then reopen the view through Show player.
3. Watch the network: about one requestUrl attempt per feed (eight with eight feeds). The cached Latest list still shows its rows, and no failure view stays on screen.

Cause: view startup calls feeds.ensureAll() (src/ui/PodcastView/PodcastView.svelte), which hydrates from the cache and also refreshes over the network, whatever the connectivity. FeedRepository has no offline gate. A related case: if the connection comes back while an offline request is still hanging, the reconnect refresh joins that request, and nothing retries until a manual refresh.

Expected: while offline, startup hydrates from the cache only and sends no request. Reconnecting refreshes once, with a fresh request.

Fix direction: separate cache hydration from network refresh, and gate the automatic refresh on the plugin's online store from #459.