多端增加手动触发压缩上下文功能

### 使用场景 / Use case

偶发上下文爆了依旧没有压缩会截断，此时需要手动压缩介入

### 当前问题 / Current limitation

偶发上下文爆了依旧没有压缩会截断

### 期望方案 / Proposed solution

多端增加手动触发压缩上下文功能

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

_No response_

The issue names no files, tests, or entry points. Start by locating the existing context-compression flow across the supported clients, then trace where a manual trigger could be exposed. Done means users on the relevant platforms can invoke compression manually before truncation, with consistent behavior across clients.

Written by the indexing model from the issue text.