fix(s16): expose saved workflows to the model

[dancvv]

Fixes #572.

The model could see the Workflow tool but not the names or purposes of the saved workflows. The tool description now lists them, and the name enum comes from the existing WORKFLOWS registry. The run and resume interfaces stay the same.

This also updates the English, Chinese, and Japanese chapter documentation and adds regression coverage for the model-facing catalog and allowed names. Web course data was regenerated with npm run extract; those snapshots were already behind current main, which accounts for the larger generated-file diff.

Validation on Python 3.12.13:

• Both discovery checks fail against the original runtime and pass with this change.
• python -m pytest tests -q: 483 passed, 100 subtests passed.
• npx tsc --noEmit from web/: passed.
• npm run build from web/: passed.
• git diff --check: passed.

AI assistance: OpenAI Codex assisted with analysis, implementation, documentation, and local validation. No live model calls were made during verification.