fix(db oauth2): Improve OAuth2 flow (#39499)

superset/exceptions.py

@@ -368,6 +368,27 @@ class OAuth2RedirectError(SupersetErrorException):
         )
 
 
+class OAuth2TokenRefreshError(OAuth2RedirectError):
+    """
+    Raised when an OAuth2 refresh token request fails with a 400/401/403 error.
+    The stored token is no longer valid and the user must re-authenticate.
+
+    Subclasses OAuth2RedirectError so that existing oauth2_exception checks
+    match it automatically, triggering start_oauth2_dance() via check_for_oauth2.
+    """
+
+    def __init__(self, response_text: str) -> None:
+        SupersetErrorException.__init__(
+            self,
+            SupersetError(
+                message="OAuth2 token refresh failed, re-authentication required.",
+                error_type=SupersetErrorType.OAUTH2_REDIRECT,
+                level=ErrorLevel.WARNING,
+                extra={"error": response_text},
+            ),
+        )
+
+
 class OAuth2Error(SupersetErrorException):
     """
     Exception for when OAuth2 goes wrong.