Press '?' to open a styled overlay showing all keyboard shortcuts,
Esc to close. Lists Space (play/pause), arrow keys (seek/volume),
F (fullscreen), M (mute), ? (help), Esc (close).
Files:
- frontend/app.js: toggleShortcutHelp(), wireShortcutHelp(), '?' and Esc handlers
- frontend/index.html: shortcut-overlay markup with .shortcut-grid
- frontend/styles.css: .shortcut-overlay, .shortcut-panel, .shortcut-row, kbd styles
Replace bare 'Searching…' text with 8 animated skeleton cards that
mirror the real card layout (thumbnail, title, channel, menu dot).
Shimmer animation sweeps across placeholder blocks until results arrive.
Files:
- frontend/app.js: showSearchSkeletons() function, wired into search submit
- frontend/styles.css: .skeleton-card, .skeleton-shimmer, .skeleton-line, .skeleton-dot styles with shimmer animation
