### Check for existing issues

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

### What happened?

AllowedFailsPolicy defines InternalServerErrorAllowedFails as a field in litellm/types/router.py, but get_allowed_fails_from_policy() in litellm/router.py (line ~11652) does not have a branch for InternalServerError.

The method handles 5 error types (AuthenticationError, Timeout, RateLimitError, ContentPolicyViolationError, BadRequestError) but is missing InternalServerError. As a result, the setting is accepted in config but silently ignored at runtime, falling back to the global allowed_fails value.

Expected behavior: When InternalServerErrorAllowedFails: 2 is configured, a deployment should be cooled down after 2 InternalServerError failures.

Actual behavior: The InternalServerErrorAllowedFails value is never read. get_allowed_fails_from_policy returns None for InternalServerError, so the router falls back to the global allowed_fails (e.g. 10000), effectively disabling cooldown for this error type.

Expected fix: Add the missing branch in get_allowed_fails_from_policy:

if isinstance(exception, litellm.InternalServerError) and allowed_…