fix: 更新main.py逻辑

config/database/milvus.py

@@ -24,6 +24,16 @@ def client() -> AsyncMilvusClient:
     return _client
 
 
+async def ensure_database(milvus_client: AsyncMilvusClient | None = None) -> None:
+    """Create the configured project database only when it does not exist."""
+    target = milvus_client or client()
+    database_name = settings.milvus.db_name
+    if not database_name:
+        raise RuntimeError("MILVUS_DB must be configured")
+    if database_name not in await target.list_databases():
+        await target.create_database(database_name)
+
+
 async def init_db() -> None:
     client()  # 急切建连；失败由注册表重试（config/database/__init__.py）
 
@@ -36,4 +46,4 @@ async def dispose() -> None:
 
 
 async def check_health() -> None:
-    await client().get_server_version()
+    await client().get_server_version()