Headless driver-station access for a desktop agent

[vafc21]

Summary

Adds a headless way for a desktop AI agent (or any script) to drive the robot's driver station without the Godot UI: a persistent ds_agentd daemon owning one RobocolClient, and a one-shot JSON CLI ds_agent that talks to it over a Unix domain socket. Full command parity with ds_cli (list, init, run, stop, restart, config commands, device-types, scan, lynx-modules, gamepad, status, watch).

This PR carries the deck-station side:

• docs/superpowers/specs/2026-09-10-headless-driver-station-agent-design.md — design spec (architecture, socket lifecycle, IPC protocol, command table, error codes, testing, rollout).
• docs/superpowers/plans/2026-09-10-headless-driver-station-agent.md — the implementation plan it was built from.
• README.md — new "Headless: letting an agent drive" section with cargo run -p ds_agent examples.

Depends on

The code itself lives in the robocol submodule (new workspace crates ds_agent_ipc, ds_agentd, ds_agent next to ds_cli), on branch headless-agent (16 commits over 0fe3d2c, head 74f26fc, scripts/lint.sh green: 28 unit + 2 end-to-end tests against fake_rc). That branch is up as whitehml/robocol#4, and the last commit here bumps external/robocol to it. Merge the robocol PR first so the submodule pointer lands on a commit reachable from its main.

Test plan

• robocol headless-agent pushed as Add ds_agentd/ds_agent: headless JSON driver station for agents robocol#4; external/robocol bumped here
• cargo run -p ds_agent -- status from external/robocol auto-starts the daemon and reports connected
• With a Control Hub or fake_rc: list → init <name> → run → stop → watch --types telemetry

🤖 Generated with Claude Code

[whitehml]

Don't commit completed or solo plan files to the repo. I'd recommend adding docs/superpowers to a .git/info/exclude file in your clone of the repo. https://dev.to/fronkan/a-personal-gitignore-even-for-a-single-repository-4o7h - for other options as well

[whitehml]

Also given that the entire control surface here is cd into the external source and initiate from the command line, we don't need to update this repository at all.