fix(playback): show the Up next card near the real end of an episode

The card appeared a fixed 8 minutes before the end: most of a short
episode, and far into the story of a long one, with no way to hide it.

- Adaptive lead: 4% of the episode, clamped to 40 s … 3 min.
- A closing-credits chapter in the last third, when timeline segments
  carry one, brings the card forward to its start (capped at 5 min).
- Close button and Escape dismiss the card for the current next episode.
- After 10 s (not while hovered) the card collapses into a one-line pill.
- Seconds countdown in the last minute.
- New playback setting "Up next card" (default on) turns it off.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/workspace/shell/util/src/lib/settings-search/settings-search-entries-playback.ts

@@ -52,6 +52,14 @@ export const PLAYBACK_SETTINGS_SEARCH_ENTRIES: readonly SettingsSearchEntry[] =
             keywords: ['up next', 'next episode', 'autoplay'],
             fallbackId: 'video-player',
         },
+        {
+            id: 'player-up-next-card',
+            section: 'playback',
+            labelKey: 'SETTINGS.PLAYER_UP_NEXT_CARD',
+            descriptionKey: 'SETTINGS.PLAYER_UP_NEXT_CARD_DESCRIPTION',
+            keywords: ['up next', 'next episode', 'credits', 'popup'],
+            fallbackId: 'video-player',
+        },
         {
             id: 'fullscreen-channel-panel',
             section: 'playback',