docs(release): prepare v1.2.0

[typelicious]

Summary

• bump FoundryGate and CLI package versions to 1.2.0
• move workstation and packaging notes into the v1.2.0 changelog section
• update release docs and roadmap status for the shipped v1.2.0 baseline

Testing

• PYTHONPYCACHEPREFIX="/Users/andrelange/.codex/worktrees/257a/ClawGate/.pycache" python3 -m compileall foundrygate tests
• PYTHONPATH=. ./.venv-check-313/bin/pytest -q
• ./.venv-check-313/bin/ruff check .
• ./.venv-check-313/bin/ruff format --check .
• ./.venv-check-313/bin/python -m build --no-isolation
• ./.venv-check-313/bin/python -m twine check dist/foundrygate-1.2.0.tar.gz dist/foundrygate-1.2.0-py3-none-any.whl
• PATH=/opt/homebrew/bin:/Users/andrelange/.cargo/bin:/Users/andrelange/.codex/tmp/arg0/codex-arg0KNkFOC:/usr/bin:/bin:/usr/sbin:/sbin:/Applications/Codex.app/Contents/Resources /opt/homebrew/bin/node packages/foundrygate-cli/bin/foundrygate.js --help
• cd packages/foundrygate-cli && npm_config_cache=/tmp/foundrygate-npm-cache PATH=/opt/homebrew/bin:/Users/andrelange/.cargo/bin:/Users/andrelange/.codex/tmp/arg0/codex-arg0KNkFOC:/usr/bin:/bin:/usr/sbin:/sbin:/Applications/Codex.app/Contents/Resources /opt/homebrew/bin/npm pack --dry-run
• ruby -c Formula/foundrygate.rb
• git diff --check