feat(engagement): video dislike + creator heart + creator pin

Three features that depend on the two additive migrations shipped in
the same commit (safe defaults, cascading foreign keys, no data loss
possible).

## Dislike button
- New video_dislikes table (migration 2026_10_21_000001) with the same
  shape as video_likes.
- Video model: dislikes() relation + isDislikedBy() / getDislikeCount
  Attribute() helpers mirroring the like pair.
- UserController@toggleDislike: endpoint behind POST
  /videos/{video}/toggle-dislike. Mutually exclusive with like — the
  toggle*Like / toggle*Dislike controllers detach the opposite state
  so a user is in exactly one of {liked, disliked, neither}. YouTube
  parity.
- video-actions component: a second thumbs-down button next to the
  existing like. Both reconcile in parallel on either response so the
  UI pair always reflects the authoritative server state.

## Creator heart + pin
- comments table gains hearted + pinned boolean columns (migration
  2026_10_21_000002, both default false, pinned is indexed).
- CommentController@heart + @pin: 403 for anyone but the video owner;
  pin() also rejects nested replies (422) and auto-unpins the
  previously-pinned top-level comment so the "at most one pinned"
  invariant is enforced at the DB level.
- Comment component:
    - Pinned comments render ahead of everything else; reorder()
      clears the comments() relation's default ->latest() so pinned
      DESC becomes the PRIMARY sort instead of a tiebreaker.
    - Creator sees heart + pin toggle buttons in the action bar.
    - Hearted comments carry a small red heart badge in the meta row.
    - Pinned comments carry a "Pinned by {creator}" header and a
      red left accent so they're visually distinct from the stream.

## Tests (9 new, 63 total)
- Dislike toggle adds/removes the row.
- Disliking clears an existing like and vice versa.
- Owner can heart; non-owner gets 403.
- Only one comment pinned at a time; replies can't be pinned (422);
  non-owner gets 403.
- Pinned comments render before newer unpinned ones.

## Deploy note
Running the migrations against the live DB needs:
    php artisan migrate

The two migration files are additive and reversible via `migrate:rollback`.

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

app/Http/Controllers/CommentController.php

@@ -206,4 +206,56 @@ class CommentController extends Controller
 
         return response()->json(['liked' => $liked, 'count' => $count]);
     }
+
+    /**
+     * Toggle the "creator heart" on a comment. Only the video owner can
+     * drop a heart; anyone else gets a 403.
+     */
+    public function heart(Comment $comment)
+    {
+        $video = $comment->video;
+        if (! $video || $video->user_id !== Auth::id()) {
+            return response()->json(['error' => 'Only the video owner can heart a comment.'], 403);
+        }
+
+        $comment->hearted = ! $comment->hearted;
+        $comment->save();
+
+        return response()->json([
+            'hearted' => (bool) $comment->hearted,
+        ]);
+    }
+
+    /**
+     * Toggle "pinned" on a top-level comment. Only the video owner can
+     * pin, and pinned comments sort ahead of everything else in the list.
+     * At most one comment is pinned at a time — pinning a new one unpins
+     * the previous.
+     */
+    public function pin(Comment $comment)
+    {
+        $video = $comment->video;
+        if (! $video || $video->user_id !== Auth::id()) {
+            return response()->json(['error' => 'Only the video owner can pin a comment.'], 403);
+        }
+        if ($comment->parent_id) {
+            return response()->json(['error' => 'Only top-level comments can be pinned.'], 422);
+        }
+
+        $wasPinned = (bool) $comment->pinned;
+        if (! $wasPinned) {
+            // Unpin any previously-pinned comment on this video first so
+            // the UI invariant "at most one pinned" is maintained at the
+            // DB level, not just in the view.
+            Comment::where('video_id', $video->id)
+                ->where('pinned', true)
+                ->update(['pinned' => false]);
+        }
+        $comment->pinned = ! $wasPinned;
+        $comment->save();
+
+        return response()->json([
+            'pinned' => (bool) $comment->pinned,
+        ]);
+    }
 }