feat: add local HTTP remote worker starter

[hyeokjun32]

Summary

• Added a local HTTP remote worker starter for explicit remote-dispatch success-path smoke validation.
• Added local HTTP registry/request examples and test coverage for the starter response contract.
• Documented the boundary as a starter path, not production remote execution.

Validation

• PYTHONDONTWRITEBYTECODE=1 .venv/bin/python -m pytest tests/test_remote_dispatch.py -q -p no:cacheprovider
• PYTHONDONTWRITEBYTECODE=1 .venv/bin/python -m pytest -q -p no:cacheprovider
• Local HTTP starter smoke with --execute-plan
• git diff --check

Notes

• Local socket bind is skipped in sandboxed pytest environments, but the explicit local HTTP smoke was verified with socket access.
• No production remote execution, heartbeat, auth, or fallback execution was added.