Chunked video upload, persistent track order, per-track playlist entries

Chunked uploads: bypass Cloudflare's 100 MB request cap by slicing the
video/audio into 8 MB chunks and reassembling server-side before the
normal store flow runs.

Track reorder: audio tracks gain a `position` column so a user's edit-
modal ordering survives reload. `Video::audioTracks()` now orders by
position, `promote_track_id` remembers the swapped row, and freshly
uploaded tracks append to the end.

Playlist per-track pinning: `playlist_videos.audio_track_id` remembers
which language the user pinned when adding a song. Same song with a
different track becomes a separate row (Spotify-style duplicates).
Player-data exposes `active_stream_url` + `active_track_id`, sidebar
cards render `?track=` from the pivot, and both `plTransitionTo` and
initial-load code activate the corresponding language option.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

app/Http/Controllers/PlaylistController.php

@@ -323,7 +323,8 @@ class PlaylistController extends Controller
         }
 
         $request->validate([
-            'video_id' => 'required|exists:videos,id',
+            'video_id'       => 'required|exists:videos,id',
+            'audio_track_id' => 'nullable|integer|exists:video_audio_tracks,id',
         ]);
 
         $video = Video::findOrFail($request->video_id);
@@ -333,7 +334,13 @@ class PlaylistController extends Controller
             abort(403, 'You cannot add this video to your playlist.');
         }
 
-        $added = $playlist->addVideo($video);
+        // Track must actually belong to this video (avoid arbitrary FK pinning).
+        $audioTrackId = $request->input('audio_track_id');
+        if ($audioTrackId && ! $video->audioTracks()->whereKey($audioTrackId)->exists()) {
+            $audioTrackId = null;
+        }
+
+        $added = $playlist->addVideo($video, $audioTrackId ? (int) $audioTrackId : null);
 
         if ($request->expectsJson() || $request->ajax()) {
             return response()->json([
@@ -353,9 +360,30 @@ class PlaylistController extends Controller
      */
     public function removeVideoByBody(Request $request, Playlist $playlist)
     {
-        $request->validate(['video_id' => 'required|exists:videos,id']);
+        $request->validate([
+            'video_id'       => 'required|exists:videos,id',
+            'audio_track_id' => 'nullable|integer',
+        ]);
+
+        if (! $playlist->canEdit(Auth::user())) {
+            abort(403, 'You do not have permission to edit this playlist.');
+        }
+
         $video = Video::findOrFail($request->video_id);
-        return $this->removeVideo($request, $playlist, $video);
+        $trackId = $request->filled('audio_track_id')
+            ? (int) $request->input('audio_track_id')
+            : null;
+
+        $removed = $playlist->removeVideoWithTrack($video, $trackId);
+
+        if ($request->expectsJson() || $request->ajax()) {
+            return response()->json([
+                'success' => true,
+                'message' => $removed ? 'Video removed from playlist.' : 'Video was not in the playlist.',
+                'video_count' => $playlist->video_count,
+            ]);
+        }
+        return back()->with('success', 'Video removed from playlist.');
     }
 
     // Remove video from playlist
@@ -431,6 +459,17 @@ class PlaylistController extends Controller
                 'visibility' => $p->visibility,
                 'thumbnail_url' => $p->thumbnail_url,
                 'video_ids' => $p->videos()->pluck('videos.id')->toArray(),
+                // Track-aware entries: each row = {video_id, audio_track_id or null}.
+                // Consumers that need per-track granularity use this; older callers
+                // can still rely on video_ids above.
+                'entries' => \DB::table('playlist_videos')
+                    ->where('playlist_id', $p->id)
+                    ->select('video_id', 'audio_track_id')
+                    ->get()
+                    ->map(fn ($r) => [
+                        'video_id'       => (int) $r->video_id,
+                        'audio_track_id' => $r->audio_track_id ? (int) $r->audio_track_id : null,
+                    ])->all(),
             ];
         });