### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

`temp_budget_increase` / `temp_budget_expiry` (set via `/key/update`) are silently ignored for any virtual key whose budget is configured through `budget_limits` (the multi-window daily/weekly/monthly style) instead of a single `max_budget`. The metadata is saved and shows up in `/key/info`, but it has no effect on request authorization — the key keeps getting `BudgetExceededError` as if no boost were set.

### Steps to Reproduce

1. Create/update a key with `budget_limits` set, e.g.: ```json { "budget_limits": [ {"budget_duration": "24h", "max_budget": 250}, {"budget_duration": "7d", "max_budget": 300}, {"budget_duration": "30d", "max_budget": 500} ] } ``` Note: `max_budget` (the top-level field) is left unset (`null`). 2. Once the key's 30d window spend reaches/exceeds 500, requests start failing with: ``` litellm.exceptions.BudgetExceededError: ExceededBudget: Key over 30d budget. Spend=$500.1658, Limit=$500.00 ``` 3. Grant a temporary boost via `/key/update`: ```json {"temp_budget…