fix(macos): harden renderer visibility verification

[rwang23]

Summary / 摘要

• Harden macOS renderer readiness so sized DOM nodes are not automatically treated as visible.
• Retry transient Runtime.evaluate failures during document swaps within the existing bounded deadline.

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

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) / 若改了安装恢复启动则做过恢复再应用

User-facing / 用户可见变更

• Updated macos/CHANGELOG.md (and macos/VERSION if release-worthy) / 已更新 changelog（发版时再 bump VERSION）
• N/A — no user-facing change / 无用户可见变更

Security / 安全

• Does not modify official Codex install / asar / signatures / 未修改官方安装与签名
• Does not silently write API Base URL or keys / 未静默写入 API Base URL 或 Key
• CDP remains loopback-oriented (127.0.0.1) where applicable / CDP 仍仅本机回环（如适用）

Notes / 补充

Root cause: the previous box() check accepted any nonzero-size node unless it
had display:none or visibility:hidden, and one transient evaluation error
aborted the entire verify loop.

Changes reject detached, opacity-zero, CSS-hidden, content-visibility:hidden,
and offscreen anchors; use checkVisibility() when present; and retry until the
existing deadline expires.

Validated on main@611c101 with:

• node --test macos/tests/renderer-verification.test.mjs — passed (4 tests)
• Git Bash syntax check of every macos/scripts/*.sh — passed
• git diff --check — passed

The full portable macOS Node suite was attempted on this Windows host. Its new
test passed, while three pre-existing platform-dependent tests could not run
because Windows denied symlink creation or lacks /bin/bash; macOS CI and a
real Verify smoke remain required.

Tracking issue / 追踪 Issue

Closes #294