fix(trash)+refactor(file life cycle)

* fix issue with the empty trash (wasn't calling thumbnail clean up)
 * refactor file service life cycle (TrashService don't call directly ThumbnailService, but call the on_file_deleted() hook
 * remove unused mehod: _validate_user_ownership()

src/domain/repositories/trash_repository.rs

@@ -11,6 +11,11 @@ pub trait TrashRepository: Send + Sync {
     async fn delete_permanently(&self, id: &Uuid, user_id: &Uuid) -> Result<()>;
     async fn clear_trash(&self, user_id: &Uuid) -> Result<()>;
 
+    /// All trashed file IDs for this user, regardless of parent folder trash status.
+    /// Used by empty_trash for thumbnail cleanup — the view used by get_trash_items
+    /// excludes files inside trashed folders, which would miss their ext thumbnails.
+    async fn get_all_trashed_file_ids(&self, user_id: &Uuid) -> Result<Vec<String>>;
+
     /// Bulk-delete all expired trash items (files + folders) in a single
     /// transaction.  Returns `(files_deleted, folders_deleted)`.
     async fn delete_expired_bulk(&self) -> Result<(u64, u64)>;