docs-pr-checklisted

# docs-pr-check — CI gate for documentation hygiene on pull requests Generates a GitHub Actions workflow that runs on every pull request and enforces three documentation quality checks: code-to-docs change ratio, frontmatter validity, and internal link integrity. ## Workflow 1. **Receive configuration** — accept the `block_on_broken_links` flag (default `false`) that controls whether broken links fail the build or are reported as warnings only. 2. **Render the workflow file** — produce a GitHub Actions workflow configured with the supplied settings. The workflow triggers on `pull_request` and runs three jobs. 3. **Write to the repository** — place the workflow at `.github/workflows/docsbook-docs-check.yml`, creating the directory if it does not exist. Overwrite if the file already exists. 4. **Report** — print the output path, the effective `block_on_broken_links` value, and a reminder to commit and open a PR to activate the check. ## Guardrails - Do not modify any existing workflow files other than `docsbook-docs-check.yml`. - The workflow must use `continue-on-error: true` on the broken-links job when `block_on_broken_links` is `false`; only set it to `false` (blocking) when the flag is explicitly `true`. - Never run the checks against the base branch — only the changed files in the PR diff. - Frontmatter validation must not fail on missing optional fields; only required fields (`title`, `description`) trigger an error. ## Acceptance Criteria - [ ] Workflow file writ