fix: import worker error handling

tiku-server/app/routers/import_.py

@@ -32,8 +32,14 @@ def _import_worker():
         task_id, tmp_path, import_type, source_name, config = task
         try:
             _process_import(task_id, tmp_path, import_type, source_name, config)
-        except Exception:
-            pass
+        except Exception as e:
+            conn = get_connection(config.db_path)
+            try:
+                update_import_task(conn, task_id, status="error", message=str(e))
+            except Exception:
+                pass
+            finally:
+                conn.close()
         _import_queue.task_done()
 
 # 启动后台工作线程