frontend: add username login

core/data/schema/user.py

@@ -120,3 +120,7 @@ class UserData(BaseData):
 
         result = await self.execute(sql)
         return result is not None
+
+    async def get_user_by_username(self, username: str) -> Optional[Row]:
+        result = await self.execute(aime_user.select(aime_user.c.username == username))
+        if result: return result.fetchone()