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/bmb/workflows/create-workflow/steps/step-09-complete.md

@@ -156,7 +156,7 @@ Update {workflowPlanFile} frontmatter:
 
 Display: **Workflow Creation Complete!** [T] Test Workflow [M] Make Adjustments [D] Get Help
 
-#### Menu Handling Logic:
+### Menu Handling Logic:
 
 - IF T: Offer to run the newly created workflow with sample data
 - IF M: Offer to make specific adjustments to the workflow