Add public readiness docs and smoke workflow

[darious]

Summary

• add AGPL-3.0-only license, contribution, conduct, security, and third-party notice docs
• add a fast always-running repository smoke workflow for branch protection
• add AGPL metadata to Python and frontend manifests
• tighten ignores for local Codex files, env files, Android signing files, and build artifacts

Validation

• parsed pyproject.toml
• parsed web package.json and package-lock.json
• ran the repository smoke checks locally