fix: switch frontend login to authentik auth-code flow

app/schemas/login.py

@@ -11,3 +11,12 @@ class LoginResponse(BaseModel):
     token_type: str = "Bearer"
     expires_in: int | None = None
     scope: str | None = None
+
+
+class OIDCAuthUrlResponse(BaseModel):
+    authorize_url: str
+
+
+class OIDCCodeExchangeRequest(BaseModel):
+    code: str
+    redirect_uri: str