- Watched: an explicit toggle in the modal (Mark watched / Watched→unmark) plus
auto-mark when playback reaches the end (within 10s, or on the ended event).
- Compact layout: drop the header bar and the redundant 'Open on YouTube' button
(the embed's own YouTube logo already jumps out); Close moves to the title row,
channel + meta share one line — fits without a scrollbar at higher zoom.
- Card actions reflect status: watched shows a double-check, saved a filled
bookmark, with matching tooltips.
- Description: new GET /api/videos/{id} exposes the already-stored description,
shown in a popover when hovering the modal title (fetched lazily).
Left-clicking a feed card (Ctrl/Cmd/middle still open youtube.com in a new tab)
opens a modal that plays the video in-app via the YouTube IFrame Player API
instead of leaving the app. Using the JS API (not a bare embed) lets us read the
playback position: it's checkpointed per-video in localStorage and on close, and
restored via the 'start' param when the video is reopened. The modal closes via
a header button, the backdrop, or ESC (ESC only while focus is on our page — a
cross-origin iframe owns its own key events).
