fix(feeds): skip automatic requests while offline - #474

Summary

Opening PodNotes offline now shows cached episodes without automatic feed requests. Reconnecting refreshes missing or expired feeds once. ensureAll hydrates before applying the online gate, so an automatic offline request cannot absorb the reconnect refresh.

Fixes #460

Verification

• Passed npm run lint, npm run format:check, npm run typecheck, npm run build, npm run test with 2,558 tests, npm run test:tooling with 13 tests, and npm run docs:build. Commands used Node 22 through fnm exec --using 22 --.
• Passed npm run test:e2e on a fresh isolated vault in Obsidian 1.14.4 on Linux, then with PODNOTES_OBSIDIAN_APP=/opt/Obsidian/obsidian on 1.13.7, with 188 tests each. With two expired fixture feeds and a stopped server, offline attempts fell from 2 to 0. Holding the baseline requests reproduced 0 fresh reconnect attempts; the fix made exactly 2 and updated both lists. Fixtures use http://podnotes.test:<port>/feed2-alpha/feed.xml and /feed2-beta/feed.xml.
• npm run count:writes -- start, report, and stop recorded 3 completed writes before and after the fix, with 0 failures. npm run size passed at 99,052 gzip bytes, an increase of 15 bytes. Runtime screenshot.

Verification logs and review reports include the failing baseline, passing runs, and mutation scripts.

Four wrong alternatives each failed a named test:

• Read navigator.onLine instead of the online store. automatic loading follows the online store and reconnect starts a fresh request failed.
• Skip offline hydration. offline, an expired cache shows without a request failed.
• Ignore subscription changes. subscription changes load only when online failed.
• Force network refreshes for fresh caches. a document is fetched again once it is more than six hours old failed.

Scope

This covers automatic startup, view opening, subscription changes, and reconnect. Refresh and Retry retain their offline behavior. Cancellation of requests started online before a drop, or explicitly through a URI while offline, remains separate work.

Release impact

No settings, storage format, public API, or URI changes. No migration.

Docs at release

Update docs/src/content/docs/podcasts.md, under When a feed cannot be reached, to explain cached lists appearing offline without automatic requests, missing or expired feeds refreshing on reconnect, and Refresh being unavailable offline. Published docs are unchanged.