feat(bmm): enhance PRD workflow with brownfield project support (#1047)

- Add three-branch conditional logic for document-based discovery:
  - PATH A: Has Product Brief (any project type)
  - PATH B: No Brief + Has Project Docs (brownfield)
  - PATH C: No Documents (greenfield from scratch)
- Add YAML frontmatter to all 12 PRD step files
- Add documentCounts to frontmatter for state tracking
- Fix step count (11 steps, not 10) and path typos
- Remove non-existent workflow references (story-context, validate-architecture)
- Update workflow chains and glossary definitions

Key insight: Branch based on DOCUMENT TYPE, not PROJECT TYPE.

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

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

src/modules/bmm/docs/workflows-implementation.md

@@ -70,7 +70,7 @@ For a visual representation of the complete workflow, see: [workflow-method-gree
 Stories move through these states in the sprint status file:
 
 1. **TODO** - Story identified but not started
-2. **IN PROGRESS** - Story being implemented (create-story → story-context → dev-story)
+2. **IN PROGRESS** - Story being implemented (create-story → dev-story)
 3. **READY FOR REVIEW** - Implementation complete, awaiting code review
 4. **DONE** - Accepted and complete