Adopt Ground Control from the published grndctl package

[Brad-Edwards]

Summary

Ground Control is now published on npm as grndctl. Set this repository up for it so agents can run the gated /implement, /quickfix, and /review workflows here. Today it has no Ground Control configuration.

Work

See the Ground Control README and Set up a repository:

1. On the host: npm install -g grndctl (Node.js 22+, gh signed in) and grndctl install-skills.
2. In this repository: grndctl init. Confirm the detected settings (project id, GitHub repo, base branch, test, completion, lint, and format commands, SonarCloud project if there is one, ADR directory). It writes .ground-control.yaml, adds the ground-control entry to .mcp.json, creates .env from the template, and makes sure .env is ignored by git.
3. Fill in .env with the credentials this repo needs (review-engine credential, and SONAR_TOKEN if the repo uses SonarCloud).
4. Run grndctl doctor and fix anything it reports, including installing the Phase E workflow.
5. Add a short note to the contributor docs saying agents in this repo run Ground Control via grndctl.

Acceptance criteria

• .ground-control.yaml is committed, and its test and completion commands actually run this repo's test suite.
• .mcp.json starts Ground Control with grndctl mcp.
• .env is gitignored and never committed.
• grndctl doctor passes in a fresh clone once .env is filled in.