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/application/services/file_lifecycle_service.rs

@@ -0,0 +1,47 @@
+use std::future::Future;
+use std::pin::Pin;
+use std::sync::Arc;
+
+use crate::application::ports::file_lifecycle::FileDeletedHook;
+
+/// Composite dispatcher for file lifecycle events.
+///
+/// Aggregates all `FileDeletedHook` implementations and fans out each event to
+/// every registered handler. Services hold a single `Arc<dyn FileDeletedHook>`
+/// pointing here — new handlers are added once, in DI, without touching the
+/// services themselves.
+pub struct FileLifecycleService {
+    deleted: Vec<Arc<dyn FileDeletedHook>>,
+}
+
+impl Default for FileLifecycleService {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl FileLifecycleService {
+    pub fn new() -> Self {
+        Self {
+            deleted: Vec::new(),
+        }
+    }
+
+    pub fn with_deleted_hook(mut self, hook: Arc<dyn FileDeletedHook>) -> Self {
+        self.deleted.push(hook);
+        self
+    }
+}
+
+impl FileDeletedHook for FileLifecycleService {
+    fn on_file_deleted<'a>(
+        &'a self,
+        file_id: &'a str,
+    ) -> Pin<Box<dyn Future<Output = ()> + Send + 'a>> {
+        Box::pin(async move {
+            for hook in &self.deleted {
+                hook.on_file_deleted(file_id).await;
+            }
+        })
+    }
+}