Fix macOS backend reconnect after sleep

[lzx8589561]

Summary

• Add a bridge watchdog to the silent macOS launcher path so a stale CDP bridge is detected and reinjected after sleep/wake.
• Preserve the launcher BridgeContext during reinjection so data routes and user script context remain available.
• Add Access-Control-Allow-Private-Network: true to helper HTTP responses so renderer fallback fetches to 127.0.0.1 are not blocked by Chromium Private Network Access checks.

Validation

• Built and manually tested an arm64 DMG on macOS: closing and reopening the MacBook no longer leaves the Codex++ menu offline while 127.0.0.1:57321 is alive.
• cargo test -p codex-plus-core default_helper_serves_backend_status_over_http
• cargo test -p codex-plus-launcher launcher_hooks_install_bridge_watchdog_for_reinjection
• cargo build --release

Notes

The build still reports existing unrelated warnings in codex-plus-core/codex-plus-launcher; this PR does not introduce new failing warnings.