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/shared/interfaces/src/lib/settings.interface.ts

@@ -151,6 +151,11 @@ export interface Settings {
      * missing values mean enabled. Only affects the built-in web players.
      */
     playerUpNextRail?: boolean;
+    /**
+     * Show the "Up next" card in the shared player controls shortly before a
+     * series episode ends. On by default; missing values mean enabled.
+     */
+    playerUpNextCard?: boolean;
     /**
      * Slide the live channel list over the video in fullscreen — resting the
      * mouse on the left edge, tapping that edge on touch, or pressing `C` —