chore: retire TODO.md in favour of workplans

Drop the repo-level Todofile; active work lives in workplans/ and State
Hub per ADR-001. Schedule prepare now surfaces workplans/ instead of
TODO.md. Gitignore .kaizen/agents/ and .kaizen/metrics/ runtime state.

CONTRIBUTING.md

@@ -45,7 +45,7 @@ This repository follows PythonVibes best practices:
 - `src/kaizen_agentic/` - Core framework source code
 - `agents/` - Specialized agent definitions (17+ agents)
 - `tests/` - Comprehensive test suite
-- `TODO.md` - Current development tasks (Keep a Todofile format)
+- `workplans/` - Active workstreams and tasks (ADR-001)
 - `CHANGELOG.md` - Version history (Keep a Changelog format)
 
 ### Making Changes
@@ -155,15 +155,15 @@ When reporting bugs, please include:
 1. **Discuss significant changes** in an issue first
 2. **Keep PRs focused** on a single feature or fix
 3. **Write clear commit messages** following conventional commit format
-4. **Update relevant documentation** including TODO.md and CHANGELOG.md
+4. **Update relevant documentation** including workplans and CHANGELOG.md
 5. **Ensure all checks pass** including tests and linting
 6. **Respond to review feedback** promptly and constructively
 
 ## Agent-Assisted Development
 
 This repository includes 17+ specialized agents to assist with development:
-- Use `todo-keeper` for TODO.md maintenance
-- Use `changelog-keeper` for CHANGELOG.md updates
+- Use `keepaChangelog` for CHANGELOG.md updates
+- Use `project-assistant` for workplan and session orientation
 - Use `contributing-keeper` for this file maintenance
 - See CLAUDE.md for complete agent catalog and usage