feat: add AI.INPUT.IM status auto switch

[zhuifengshaonian6]

Summary

• add a Codex++ user script that monitors status.input.im and selects the first healthy model by priority
• use the Codex native model callbacks and Electron fetch bridge, with browser fetch fallback
• require consecutive health confirmation for automatic switches and keep retrying after API failures
• provide a persistent 38px collapsed status control with pause, resume, and manual check actions
• register the script in index.json with a verified SHA-256

Validation

• node --check scripts/ai-input-im-status-auto-switch.js
• python -m json.tool index.json
• verified index SHA-256 matches the submitted script
• tested in Codex++ 1.2.47 on Windows: status request, current/target model discovery, native switch callback, pause/resume, and collapsed/expanded UI

[BigPizzaV3]

脚本语法和索引 SHA 校验通过，但自动切换行为需要先收紧再合并：

• 首次安装应默认暂停，必须由用户明确启用自动切换；当前默认会启用。
• Check now 应只检查状态，不能绕过连续确认后立即切换模型；若需要强制切换，请单独提供明确操作。
• 后台轮询不应为了发现 React bridge 自动点击并打开原生模型菜单，避免每分钟干扰当前交互。
• 请提交覆盖默认状态、连续确认、菜单占用、API 失败和恢复重试的自动化测试。

完成后 rebase 到最新 main 再审。