chore(core/qa): function-audit toolchain + parity/audit reports + pixel-perfect skill

- qa/function-audit: playwright 行为审计工具(audit.mjs/verify-modals.mjs/pages.json)
  + 18 页审计产出(*.audit.md/json、summary、运行日志)
- qa/visual-parity: 调试/测量辅助脚本(_dbg*.mjs/_measure.mjs/_off.mjs)
- core/还原度核对报告.md: 18 页 pixelmatch 核对结果(含 vite 代理陈旧坑记录)
- core/还原与接口待办.md: 逐页还原度/真实数据/交互接入待办总表
- .claude/skills/pixel-perfect-react: 像素级还原 React 的 SKILL 文档
- frontend/public/_devlogin.html: 临时本地登录辅助页(可删)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/frontend/public/_devlogin.html

@@ -0,0 +1 @@
+<!-- temp dev helper, safe to delete -->