Add docs command validation coverage

[alonshoa]

Problem

The docs now include many CLI, Docker, Compose, and MCP examples. Without targeted validation, documentation commands can drift from the implemented CLI and the external-project fixture.

Scope

• Keep mkdocs build --strict in CI as the baseline docs check.
• Add practical automated coverage for the minimal documented command paths where feasible.
• Validate parity between the minimal external-project tutorial and tests/fixtures/external_project or a promoted sample project.
• Prefer smoke checks for command syntax and expected outputs over expensive full visual regression.
• Consider lightweight checks for broken internal links or missing referenced docs assets.

Acceptance Criteria

• CI protects the documented minimal external-project workflow from drift.
• CI protects core studio command examples that are cheap to validate.
• The checks do not require rendering every visual asset in normal CI unless cost is explicitly accepted.
• Documentation contributors can run the checks locally.

Dependencies

Depends on the tutorial command set being stabilized by the onboarding documentation work.

Category

testing, documentation