feat: implement todofile system and retire NEXT.md

Replace NEXT.md approach with standardized Keep a Todofile V0.0.1 format
for better task management and human-AI collaboration during coding sessions.

## Todofile System Setup:
- **TODO.md**: Main todofile following Keep a Todofile V0.0.1 format
- **TODOFILE_GUIDE.md**: Comprehensive system documentation and workflow
- **Integration**: Fully integrated with existing kaizen-agentic framework
- **Agent Support**: Uses agent-keepaTodofile for maintenance

## Content Migration:
- Migrated strategic priorities from NEXT.md to TODO.md [Unreleased] section
- Preserved session success criteria and development milestones
- Organized tasks by impact type (To Add, To Fix, To Refactor)
- Archived NEXT.md to history/NEXT_archived_20251025.md

## Documentation Updates:
- README.md: Updated "Next Actions" → "Current Tasks" link
- agent-project-management.md: Updated workflow to use TODO.md
- docs/README.md: Updated project management references
- Added comprehensive TODOFILE_GUIDE.md

## Benefits:
- **Standardized Format**: Industry-standard Keep a Todofile format
- **Better Organization**: Impact-based task categorization
- **AI-Ready**: Designed for human-AI collaboration workflows
- **Context Preservation**: Maintains coding flow across session interruptions
- **Integration Ready**: Works with existing agent and capability systems

Active tasks now in TODO.md [Unreleased] section focusing on strategic
issue resolution and capability management validation.

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

Co-Authored-By: Claude <noreply@anthropic.com>

agents/agent-project-management.md

@@ -17,7 +17,7 @@ You are the MarkiTect project assistant, specialized in providing project status
 
 - **ProjectStatusDigest.md**: The canonical source of truth for project architecture, features, and current state
 - **ProjectDiary.md**: Chronological record of major work packages, milestones, and development sessions
-- **NEXT.md**: Next steps and priorities to ease transfer between coding sessions
+- **TODO.md**: Task management and priorities following Keep a Todofile format for maintaining coding flow
 - **Makefile**: Provides helpers to use and improve the capabilities provided by the project
   **Gitea Issues**: Backlog of issues and backlog of tasks stored as issues in gitea
 
@@ -125,7 +125,7 @@ When asked to help wrap up a development session, follow this standardized routi
 
 ### End-of-Session Checklist:
 1. **Update ProjectDiary.md**: Add entry documenting progress, challenges, and achievements
-2. **Update NEXT.md**: Set clear priorities and strategy for next session
+2. **Update TODO.md**: Set clear priorities and strategy for next session using todofile format
 3. **Update ProjectStatusDigest.md**: Refresh current status, metrics, and completed features
 4. **Issue Management**: Review and create any issues for sidequests and discoveries made during session
 5. **Anchor patterns**: Update this project-assistant definition with any new workflow patterns