- Implemented `/v1/completions` endpoint mirroring OpenAI's completions API specification.
- Added conversion functions to translate between completions and chat completions formats.
- Introduced streaming and non-streaming response handling for completions requests.
- Updated `server.go` to register the new endpoint and include it in the API's metadata.
- Introduced `AllowLocalhostUnauthenticated` flag allowing unauthenticated requests from localhost.
- Updated authentication middleware to bypass checks for localhost when enabled.
Add new Gemini CLI models and update model registry function
- Introduced `GetGeminiCLIModels` for updated Gemini CLI model definitions.
- Added new models: "Gemini 2.5 Flash Lite" and "Gemini 2.5 Pro".
- Updated `RegisterModels` to use `GetGeminiCLIModels` in Gemini client initialization.