Agents no longer commit task files, so when an agent safe-exits:
- Agent notifies coordinator with detailed blocking message (what happened, what was tried, suggested fix)
- Agent commits any partial source code progress and pushes
- Coordinator updates task file on main with status: blocked and the reason
- Coordinator attempts resolution, spawns new agent if resolved
Also removed stale 'task file conflicts' from merge workflow since
agents no longer commit task files.