loadMoreEpisodesForFeed's hot-cache path ran fully synchronously (no
await between getFeed and setFeeds), so the isLoadingMore spinner never
painted and keyboard input froze through every feed in a loadMoreAllFeeds
batch. Add await yieldToUI() before the setFeeds so the renderer gets a
macrotask turn to paint and process input between feeds.
Drop the "Loading…/Refreshing…/Downloading N" label text from the global
activity indicator — render the braille spinner only, per request.
Persisted feeds keep only episodes from the last 30 days (plus completed
downloads); older episodes live in volatile memory and survive refreshes
via union merge, with per-feed in-memory caches capped at 500. Refresh
batches run at FETCH_CONCURRENCY=4 with per-feed incremental apply (no
Promise.all barrier), config.json writes are trailing-edge debounced
(250ms, immediate flushPendingSave for unsubscribes), and cold
fetch-more refetches abort at FETCH_TIMEOUT_MS. A shared activity store
powers a global top-right indicator covering refresh, fetch-more,
subscribe, search, and downloads.
Also includes the in-flight incremental RSS parsing (chunked with
event-loop yields) and refresh spinner work this tree already carried.
