Adds agent creation and deletion tools to the pi extension, with engine-side implementation in `agent-tools.ts`, core store integration for agent lifecycle management, and corresponding tests and documentation updates across the workspace.
Fusion-Task-Id: FN-3777
The merge completes FN-3320 by implementing configuration tools for the agent system (`agent-tools.ts`), wiring them through the executor, and adding test coverage (`agent-tools-config.test.ts`). Documentation was updated in `AGENTS.md` and the engine tools reference, with minor updates to the agent
Fusion-Task-Id: FN-3320
