v1.9.1

Prebuilt images: you can now run auto-browser without building it. Nothing else changes for
users; the client, LangChain and MCP bridge packages are unchanged apart from their version.

Added

• Prebuilt Docker images on GHCR (thanks @FRFlo, #151):
  ghcr.io/lvcidpsyche/auto-browser-controller and ghcr.io/lvcidpsyche/auto-browser-browser-node.
  Run them with docker compose -f docker-compose.yml -f docker-compose.images.yml up -d;
  AUTO_BROWSER_IMAGE_TAG picks latest (default), a release such as 1.9.1, or edge.
  Every push to main publishes edge and sha-<commit>. Release tags publish X.Y.Z, X.Y and
  latest, and only from a tag on main whose version matches the packages. Each image carries an
  SBOM and a build-provenance attestation:
  gh attestation verify oci://ghcr.io/lvcidpsyche/auto-browser-controller:1.9.1 -R LvcidPsyche/auto-browser.
  The images are linux/amd64. The controller image is built without the agent CLIs, so
  *_AUTH_MODE=cli still needs a local build with INSTALL_AGENT_CLIS=true.

Changed

• Controller dependencies: FastAPI >=0.142.2,<0.143 (#173); ruff 0.16.10 and cryptography
  50.0.2 (#172).