docs(release): prepare v1.0.0

[typelicious]

What changed

• bump FoundryGate to 1.0.0 in package and app metadata
• finalize the v1.0.0 changelog and release guide
• streamline the root README into a shorter landing page
• move deeper API, configuration, and operations detail into dedicated docs pages

Why

• v1.0.0 is ready to ship
• the release notes and package metadata need to match the shipped runtime
• the root README now stays easier to scan while keeping the deeper operational detail in docs

How verified

• 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-1.0.0.tar.gz dist/foundrygate-1.0.0-py3-none-any.whl
• /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
• /usr/bin/git diff --check