fix(extension): bound request-help cleanup wait

[dvd233]

Summary

• Bound the request-help cleanup wait to 1 second when the content script has already reported a user decision.
• Keep cleanup best-effort, but do not hold the daemon RPC open forever when tabs.sendMessage or notification cleanup never settles.
• Added a regression test for a hanging cleanup transport.

Fixes #277

Root cause

finishHelpFromContent waits for cleanupHelp before resolving the request. That cleanup awaits browser messaging without a deadline, so a hung message channel can outlive the daemon's cleanup grace and surface as request-help timed out and cleanup could not be confirmed.

The fix preserves the existing wait when cleanup completes normally and only falls back after the bounded budget.

Validation

• Regression red on the base commit: the new test timed out at 5 seconds.
• vitest run src/tools/__tests__/human-loop.test.ts: 30 passed.
• Extension typecheck: passed.
• Full extension suite: 1,857 passed, 103 skipped, 14 files skipped by repository configuration.
• Extension production build: passed.
• git diff --check: passed.