stage.corkboards.me update

Changes deployed to stage.corkboards.me for testing:
- Dismissed notes now have an 'undo' option that lasts 20 seconds
- Nested nevents should render more consistently
- Video filter includes: a) video note kinds b) links to video on platforms c) direct video file links
- Video player shows loading progress and 'open in new tab' fallback
- Columns save on a per-corkboard, per-device basis, and columns can now be changed on mobile (default 1)
- Threads should load with relevant context / entire thread more consistently
- 'Referenced Note Not Found' should appear less frequently
- Reacted-to content should render in threads more consistently
- If 'Load Newer' finds no notes, it still resets the 'time-since' indicator
- Saved for Later tab changes: Green/Red triangles appear without hovering; clicking the text area of a minimized 'Saved for Later' note opens it instead of opening the thread modal; removed superfluous chevron and 'no notes found' message; setting of which notes are minimized and which are open is saved to backup