New ytsage/utils/ytsage_library_manager.py: sagetube_library.db
(separate from the upstream download-history DB) with WAL from day one,
holding subscriptions, cached feed_items, watch_history with resume
positions, and the persisted play_queue. Watch history and queue tables
are wired up by the next commit.
FeedPage:
- Local mode: FeedRefreshWorker refreshes each subscribed channel
sequentially (feed.per_channel_items, default 15) and the grid fills
incrementally per channel; results are cached so the feed is
populated instantly on startup.
- Account mode: fetches youtube.com/feed/subscriptions with the user's
browser cookies - the real logged-in feed; the option is enabled only
while cookies are active and errors surface as a status banner.
- Sidebar lists subscriptions (double-click opens the channel in
Browse; context menu unsubscribes). Browse's Subscribe button now
toggles subscription state through the Feed page.
Verified live: subscribe -> refresh -> 15 videos cached in SQLite and
rendered as cards.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Jaroslav Beneš