fix: Share-View Loeschen nutzt jetzt Papierkorb statt hartem Delete

- share_delete_file nutzt _trash_recursive() statt db.session.delete()
- Geloeschte Dateien aus Share-Links landen im Papierkorb des Eigentümers
- Share-Dateiliste filtert getrashte Dateien aus (is_trashed=False)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/files.py

@@ -696,7 +696,7 @@ def share_list_files(token):
         if not target_parent or not _is_inside_shared_folder(target_parent, shared_folder.id):
             return jsonify({'error': 'Zugriff verweigert'}), 403
 
-    files = File.query.filter_by(parent_id=parent_id)\
+    files = File.query.filter_by(parent_id=parent_id, is_trashed=False)\
         .order_by(File.is_folder.desc(), File.name).all()
 
     # Build breadcrumb from current parent back to shared root
@@ -821,15 +821,10 @@ def share_delete_file(token, file_id):
     if not _is_inside_shared_folder(target_file, link.file_id):
         return jsonify({'error': 'Datei gehoert nicht zu diesem Ordner'}), 403
 
-    # Delete from disk
-    if target_file.storage_path:
-        filepath = Path(current_app.config['UPLOAD_PATH']) / str(target_file.owner_id) / target_file.storage_path
-        if filepath.exists():
-            filepath.unlink()
-
-    db.session.delete(target_file)
+    # Soft-delete: move to trash
+    _trash_recursive(target_file)
     db.session.commit()
-    return jsonify({'message': 'Datei geloescht'}), 200
+    return jsonify({'message': 'In Papierkorb verschoben'}), 200
 
 
 @api_bp.route('/share/<token>/verify', methods=['POST'])