feat(quality): add markdownlint-cli2 to quality checks (#1039)

- Add markdownlint-cli2 as dev dependency
- Add lint:md script to package.json
- Add markdownlint job to CI workflow
- Configure 5 rules: heading-increment, no-duplicate-heading,
  no-trailing-punctuation, no-bare-urls, no-space-in-emphasis
- Fix existing violations across 19 markdown files
- No auto-fix to prevent destructive changes

Closes #1034

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Brian <bmadcode@gmail.com>

src/modules/bmm/docs/workflow-document-project-reference.md

@@ -57,7 +57,7 @@ Choose the right scan depth for your needs:
 - Initial understanding of project structure
 - Planning next steps before deeper analysis
 
-**Does NOT read:** Source code files (_.js, _.ts, _.py, _.go, etc.)
+**Does NOT read:** Source code files (`_.js`, `_.ts`, `_.py`, `_.go`, etc.)
 
 ### 2. Deep Scan