GitLab

- Remove Gemini platform exclusion from model restriction UI in
  Create/Edit account modals (Gemini now supports model_mapping)
- Remove outdated Gemini model passthrough info cards
- Add model_mapping field to GeminiCredentials type
- Extend warmup request interception toggle to Antigravity platform
- Remove redundant try/catch in API key account creation
- Remove noisy gateway.request_completed debug log
- Reorganize Gemini model mapping sections in constants.go