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>

docs/README.md

@@ -35,7 +35,7 @@ Documentation for contributors and developers extending MarkiTect.
 ### Project Management
 - [Project Status](../history/ProjectStatusDigest.md) - Current development status
 - [Roadmap](../history/ROADMAP.md) - Strategic development plan
-- [Next Actions](../NEXT.md) - Immediate development priorities
+- [Current Tasks](../TODO.md) - Task management using Keep a Todofile format
 
 ## Key Concepts