Fix autoplay countdown showing in repeat one queue mode

When queue mode was set to repeat one, the "Playing in N seconds"
countdown still appeared after a video ended, showing the next queued
video - then restarting the current one anyway. The video-end path
never consulted the queue mode; only playNext() did, after the
countdown had already run.

- PlayerService.backendDidFinishPlaying: restart immediately in repeat
  one mode, regardless of queue contents, player visibility, background,
  or PiP. This also fixes repeat one never looping with an empty queue.
- ExpandedPlayerSheet.isAutoPlayEnabled: false in repeat one mode, which
  gates all countdown triggers (start on ended, overlay render, re-arm
  on appear) on iOS/macOS.
- TVPlayerView.handleVideoEnded: early-return in repeat one mode so
  tvOS shows neither the countdown nor the replay controls.

Yattee/Services/Player/PlayerService.swift

@@ -3126,6 +3126,15 @@ extension PlayerService: PlayerBackendDelegate {
         saveProgressAsCompleted()
         delegate?.playerServiceDidFinishPlaying(self)
 
+        // Repeat one: restart immediately - no countdown, independent of queue contents
+        // and the auto-play-next setting (that setting governs advancing to the next video)
+        if state.queueMode == .repeatOne {
+            Task {
+                await playNext()
+            }
+            return
+        }
+
         // Auto-play immediately if player is not visible (no point showing countdown)
         // UI (ExpandedPlayerSheet) will handle countdown when player is visible
         let autoPlayEnabled = settingsManager?.queueAutoPlayNext ?? true