chore: harden repo maturity baseline

[N1ghthill]

Summary

• harden repo governance and contribution baseline with license, support, security, code of conduct, dependabot, and working pre-commit hooks
• move interface-owned planning/rendering/session summary helpers into master_control.interfaces.agent.* while keeping master_control.agent.* as compatibility re-exports
• expand CI and local quality gates with Bandit, wheel smoke, Python 3.11 support, and updated product-facing documentation

Validation

• python3 -m ruff check .
• python3 -m mypy src
• python3 -m bandit -q --severity-level medium --confidence-level medium -c pyproject.toml -r src scripts
• python3 -m unittest discover -s tests
• python3 -m pytest -q
• python3 -m compileall src
• python3 -m master_control --json doctor
• python3 -m pip wheel . --no-deps -w /tmp/mc-dist
• python3 -m pre_commit run --all-files