feat: 平台同步状态记录（last_synced_at + 前端展示最后同步时间）

app/database.py

@@ -51,15 +51,19 @@ def init_db() -> None:
 
 
 def _migrate_assets_db() -> None:
-    """轻量迁移：为已有 assets 表补充新增列（SQLite create_all 不会修改已有表结构）"""
+    """轻量迁移：为已有表补充新增列（SQLite create_all 不会修改已有表结构）"""
     import sqlalchemy as sa
 
     with assets_engine.begin() as conn:
-        if not sa.inspect(conn).has_table("assets"):
-            return
-        cols = {c["name"] for c in sa.inspect(conn).get_columns("assets")}
-        if "external_id" not in cols:
-            conn.execute(sa.text("ALTER TABLE assets ADD COLUMN external_id VARCHAR"))
+        insp = sa.inspect(conn)
+        if insp.has_table("assets"):
+            cols = {c["name"] for c in insp.get_columns("assets")}
+            if "external_id" not in cols:
+                conn.execute(sa.text("ALTER TABLE assets ADD COLUMN external_id VARCHAR"))
+        if insp.has_table("providers"):
+            cols = {c["name"] for c in insp.get_columns("providers")}
+            if "last_synced_at" not in cols:
+                conn.execute(sa.text("ALTER TABLE providers ADD COLUMN last_synced_at DATETIME"))
 
 
 def get_session() -> Generator[Session, None, None]: