refactor initialize_database to return MigrationResult and handle existing schema

app/data/schema.py

@@ -526,8 +526,18 @@ def _missing_tables() -> List[str]:
     return [name for name in REQUIRED_TABLES if name not in existing]
 
 
-def initialize_database() -> None:
+def initialize_database() -> MigrationResult:
-    """Initialize the SQLite database with all required tables."""
+  """Initialize the SQLite database with all required tables.
+
+  Returns a MigrationResult describing how many statements were executed
+  and whether the migration was skipped because the schema already exists.
+  """
+  # 如果所有表已存在，则视为跳过
+  missing = _missing_tables()
+  if not missing:
+    return MigrationResult(executed=0, skipped=True, missing_tables=list(missing))
+
+  executed = 0
   with db_session() as session:
     cursor = session.cursor()
 
@@ -535,6 +545,7 @@ def initialize_database() -> None:
     for statement in SCHEMA_STATEMENTS:
       try:
         cursor.execute(statement)
+        executed += 1
       except Exception as e:  # noqa: BLE001
         print(f"初始化数据库时出错: {e}")
         raise
@@ -550,8 +561,13 @@ def initialize_database() -> None:
           WHERE id = NEW.id;
         END;
       """)
+      executed += 1
     except Exception as e:  # noqa: BLE001
       print(f"创建触发器时出错: {e}")
       raise
 
     session.commit()
+
+  # 返回执行摘要（创建后再次检查缺失表以报告）
+  remaining = _missing_tables()
+  return MigrationResult(executed=executed, skipped=False, missing_tables=remaining)