Add durable Leash agent runtime

[superposition]

What changed

• adds durable agent task, message, and capability workflows
• adds the headful operator console and HTTP smoke coverage
• keeps manual LiDAR stops direction-aware

Why

Leash needs one coherent agent runtime and operator surface on the robot, while retaining its existing physical safety gates and typed capability boundary.

Impact

Guard can run the agent runtime and headful console as part of Leash. Qualia and external agents can observe or invoke bounded capabilities without introducing a second motor writer.

Validation

• cargo clippy --all-features --all-targets -- -D warnings
• deployed on Guard through the stacked follow-up branch with CUDA active, camera/IMU/LiDAR healthy, and physical navigation disabled