feat: 能不能直接反代Google Antigravity的Opus 4.6

### 使用场景 / Use case

蚊子肉也是肉

### 当前问题 / Current limitation

A/如此恶心的情况下，Cindy要替我们做主哇😭

### 期望方案 / Proposed solution

直接模型中可调用Google Antigravity的Opus 4.6

### 已考虑的替代方案 / Alternatives considered

_No response_

The issue provides no file, test, or entry point; begin by locating Cindy’s existing model-provider integration and clarifying the expected Google Antigravity/Opus 4.6 access requirements. Done would mean the requested model is directly callable through Cindy, with the behavior verified by an appropriate test.

Written by the indexing model from the issue text.