test+docs: services command unit tests and Tier 2 documentation

[agents-squads]

Goal

Advance Tier 2 goal: services_up_down_status_functional — needs test coverage and documentation.

Context

src/commands/services.ts implements squads services up/down/status. The command is built but has no tests. Goal target: tested on Mac + Linux, documented.

Required

Tests (test/services.test.ts)

• services up — when Docker unavailable → error message, exit gracefully
• services up — when compose file missing → error message with expected path
• services down — when no compose file → "nothing to stop" message
• services status — when no containers running → shows "No Docker containers running"
• services status — JSON output mode works
• All tests mock execSync and detectTier — no real Docker calls

Documentation (README update or new TIER2.md)

• What is Tier 2 and when to use it
• Prerequisites: Docker Desktop, engineering repo sibling
• squads services up/down/status usage with expected output
• Fallback behavior when services are unavailable

Acceptance

• npm test passes with new services tests
• npm run build passes
• Documentation is accurate and minimal (not bloated)