Remove several legacy agent configuration files from the `.kilo/` directory and add new unit tests for task CRUD operations in the backend API routes.
- delete .kilo/agent/swarm-master.md
- delete .kilo/agents/closure-gate.md
- delete .kilo/agents/mcp-backend-coder.md
- delete .kilo/agents/swarm-master.md
- delete .kilo/agents/tester.md
- add backend/src/api/routes/__tests__/test_tasks_crud.py
- update backend/src/api/routes/__tests__/conftest.py to include test database URLs