get_end_user_object raises litellm.BudgetExceededError internally
when the end-user is over budget. The previous _safe_fetch in the
centralized gate swallowed it and returned None, which caused
common_checks to see end_user_object=None and skip the budget check
entirely — silently bypassing end-user budget enforcement.
Add BudgetExceededError to the re-raise list alongside HTTPException
and ProxyException (reported by Veria AI).