feat: many category and sub can be in playlist

app/Models/MusicCategory.php

@@ -4,6 +4,7 @@
 
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;  // ← Add this
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
 use Illuminate\Database\Eloquent\Relations\HasMany;    // ← Add this
 class MusicCategory extends Model
 {
@@ -18,9 +19,9 @@ class MusicCategory extends Model
         'order' => 'integer',
     ];
 
-    public function playlists(): HasMany
+    public function playlists(): BelongsToMany
     {
-        return $this->hasMany(MusicPlaylist::class, 'category_id');
+        return $this->belongsToMany(MusicPlaylist::class, 'music_category_playlist', 'category_id', 'playlist_id');
     }
 
     public function subcategories(): HasMany
@@ -45,7 +46,7 @@ public function image(): BelongsTo
     
     public function getActivePlaylistsAttribute()
     {
-        return $this->playlists()->where('is_active', true)->get();
+        return $this->playlists()->where('music_playlists.is_active', true)->get();
     }
 
       // Total music count across all playlists and subcategories