npm install playwright pulled v1.59.1 but the Docker image ships
v1.52.0 browsers, causing a version mismatch crash. Pin to 1.52.0.
Also add ci/Dockerfile.test-runner for pre-building the image into
registry.gobha.me:5000/ci-test-runner:latest — eliminates npm install
from every CI run.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
