Add UI test for TokenRateLimitPolicy form view

## Details
TokenRateLimitPolicy form has: policy name, target gateway, limits configuration.

## Checklist
- [ ] Policy name required field validation
- [ ] Target gateway selector validation
- [ ] Limits object configuration
- [ ] Form/YAML toggle preserves data
- [ ] Form submission creates resource
- [ ] Edit mode loads existing resource
- [ ] Cancel redirects to list page
