fix(macos): stop stale injector watcher CPU loops

[jeromychu23]

Summary / 摘要

• Tie every macOS injector watcher to the verified ChatGPT host PID and stop it as soon as that host exits.
• Replace launchctl submit with a one-shot LaunchAgent using KeepAlive=false, while cleaning up legacy submitted jobs and orphaned jobs whose state file is missing.
• Back off failed CDP discovery from 250 ms to a 30-second cap, throttle repeated errors to 30 seconds, and keep SIGINT/SIGTERM interruption immediate.
• Add lifecycle, launch-agent, host-exit, retry, log-throttle, and existing window-readiness regression coverage.

Closes #218

Type / 类型

• Bug fix / 缺陷修复
• Feature / 新功能
• Docs / 文档
• Theme / CSS / visual / 主题或视觉
• Scripts / install / restore / 脚本或安装恢复
• Chore / 杂项

Platform / 平台

• macOS
• Windows
• Both / 双平台
• Docs / repo only / 仅文档或仓库元数据

Self-check / 自测

Docs-only / 仅文档

• Links and wording reviewed / 已检查链接与表述

macOS (when code under macos/ changes)

• macos/tests/run-tests.sh passed / 已通过
• Doctor (optional): macos/scripts/doctor-macos.sh
• Live verify (if inject/CSS/start path): verify-dream-skin-macos.sh or Desktop Verify
• Restore / re-apply smoke (if install/restore/start changed) / 若改了安装恢复啟動則做過恢復再應用

Windows (when code under windows/ changes)

• Relevant install / start / verify / restore scripts exercised / 已按改動跑過對應腳本
• Environment noted below (OS build, Codex source) / 下方註明環境

User-facing / 用户可见变更

• Updated macos/CHANGELOG.md (and macos/VERSION if release-worthy) / 已更新 changelog（發版時再 bump VERSION）
• N/A — no user-facing change / 無使用者可見變更

Security / 安全

• Does not modify official Codex install / asar / signatures / 未修改官方安裝與簽名
• Does not silently write API Base URL or keys / 未靜默寫入 API Base URL 或 Key
• CDP remains loopback-oriented (127.0.0.1) where applicable / CDP 仍僅本機回環（如適用）

Notes / 補充

• Based on the latest upstream main; the unrelated local add Ado theme commit was intentionally excluded.
• The current upstream renderer has already replaced the old root-class mutation path from the local CPU investigation, so this PR preserves that unified renderer and ports only the still-relevant macOS watcher/launchd fixes.
• Passed: CODEX_DREAM_SKIN_SKIP_DOCTOR=1 npm test from macos/, targeted watcher lifecycle and window-readiness tests, shell/Node syntax checks, and git diff --check.
• The suite skipped SwiftPM/XCTest because this Mac does not have a complete matching Xcode macOS platform.
• Doctor was attempted but the current live session failed at its renderer verification step; automated tests were rerun with the repository-supported Doctor skip flag. Live verify and restore/re-apply smoke remain unchecked.
• No files under windows/ changed.