refactor(todo): organize TODO items into queued and completed directories

- Update README.md to reflect new todo/ directory structure with queued/ for pending items and completed/ for historical records.
- Rename docs/TODO.md to todo/completed/MODEL_ENFORCEMENT.md.
- Add example todo/queued/TODO_ITEM.md with initial TODO steps.

README.md

@@ -438,6 +438,9 @@ grokkit/
 ├── cmd/              # CLI commands (Cobra)
 ├── config/           # Viper configuration
 ├── docs/             # Documentation
+├── todo/              # TODO tracking: queued/ (pending) and completed/ (historical record)
+│   ├── queued/        # Pending TODO items
+│   └── completed/     # Completed TODO items with history
 ├── internal/
 │   ├── errors/       # Custom error types
 │   ├── git/          # Git operations

todo/queued/TODO_ITEM.md

@@ -0,0 +1,4 @@
+# TODO ITEM 1
+- [ ] 1 step one
+- [ ] 2 step two
+- [ ] 3 step three