Add TSDoc to the public API and publish an API reference #1579

What happens

The public API has almost no doc comments. An editor hover shows a signature and nothing else:

Defaults, units and behaviour (stop() removes the container and its volumes by default, withBindMounts replaces, logs({ since }) is in seconds) are only on the docs site, where they are described per feature and not per method.

Expected

• A short TSDoc comment on every exported method and option field, covering what the code cannot say: the default, the unit, and any non-obvious behaviour.
• An API reference generated from those comments and published with the docs site.

Where

• packages/testcontainers/src/test-container.ts, types.ts and the exported classes
• mkdocs.yml and the Docs job in .github/workflows/checks.yml

Notes

• AGENTS.md asks for minimal code comments. This would be a deliberate exception for the exported API, limited to information a caller cannot get from the signature.
• Can be done one file at a time.

Dependencies

• Nothing blocks this. It can start now.
• Coordinate with Document and align the units of sizes and durations #1542: the unit documentation there is a subset of this.