SPA playlist transitions for generic (video) type

- Add _ytpLoadSource(hlsUrl, mp4Url) to video-player component:
  destroys old HLS instance, creates a new one with the new source,
  then plays — browser retains autoplay permission since the <video>
  element never leaves the page
- Add _ytpNavOverride hook: playlist overlay can replace navigateNext/
  navigatePrev without modifying the component internals
- Add _plOnVideoEnd hook to 'ended' handler so the playlist overlay
  can control autoplay/loop behavior independently
- Expose window._ytpHls for HLS instance lifecycle management
- Add hls_url + has_hls to /videos/{video}/player-data JSON endpoint
- Replace generic.blade.php playlist controls with full SPA system
  identical in structure to music type: plTransitionTo, plSwapContent,
  plAdj, plRender, plHighlight — no page refresh on track change
- Sidebar shows all playlist tracks; current track highlighted in red

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

app/Http/Controllers/VideoController.php

@@ -483,6 +483,8 @@ class VideoController extends Controller
             'id'         => $video->id,
             'key'        => $video->getRouteKey(),
             'type'       => $video->type,
+            'has_hls'    => (bool) $video->has_hls,
+            'hls_url'    => $video->has_hls ? route('videos.hls', ['video' => $video, 'file' => 'master.m3u8']) : null,
             'stream_url' => route('videos.stream', $video),
             'cover_url'  => $coverUrl,
             'slides'     => $slides,