Tracking: adopt claude-container-testing plugin to replace ad-hoc lint-in-container.sh (follow-up to #213)

[strausmann]

The disposable-container lint pattern from #213 (scripts/lint-in-container.sh — the TypeScript-5 toolchain that sidesteps the TS-7-preview / typescript-eslint@8 conflict) has been generalized into a standalone, reusable Claude Code plugin:

https://github.com/strausmann/claude-container-testing

It ships:

• a node22-lint-test template pinning exactly the versions test(tests): typecheck test files, container-based lint, close two guard holes #221 landed (eslint@10.8.1, typescript@5.9.3, unified typescript-eslint@8.67.0), baked into the image;
• Go 1.23 and Node+Postgres (Compose) templates;
• a /ctest test|lint|build|env|list|prune command that runs any repo's test/lint/build in a reproducible, toolchain-decoupled dev container (built on @devcontainers/cli, images published to ghcr and pinned by digest, CI-only publish).

mcp-dockhand could adopt it to replace the ad-hoc lint-in-container.sh. Tracking note — no action required.