api: add info about how long a user session is guaranteed to be available

api/src/dooris_api/app.py

@@ -46,6 +46,7 @@ async def get_user_info(req: Request, current_user: deps.CurrentUser) -> UserSta
     else:
         return UserStatus(
             is_logged_in=True,
+            guaranteed_session_until=datetime.fromtimestamp(current_user.id_token.exp, UTC),
             user_info=UserInfo(
                 username=current_user.id_token.preferred_username,
             )

api/src/dooris_api/models.py

@@ -1,4 +1,5 @@
 from typing import Optional
+from datetime import datetime
 from pydantic import BaseModel
 from simple_openid_connect.data import IdToken
 
@@ -13,5 +14,6 @@ class UserInfo(BaseModel):
 
 class UserStatus(BaseModel):
     is_logged_in: bool
+    guaranteed_session_until: datetime
     user_info: Optional[UserInfo]