CLI: agentmetry detections <correlation_id>

[blitzcrieg1]

You can query a session's detections over HTTP, but there's no CLI shortcut. A one-liner would be handy for incident triage.

Task

Add a detections subcommand in apps/orchestrator/cli/__init__.py that calls GET /api/v1/audit/detections/{correlation_id} and prints the results as a readable table (rule, severity, summary). Mirror how the existing replay command reads from the API.

Acceptance criteria

• agentmetry detections <id> prints ranked detections, or "no detections" cleanly.
• Handles the "server not running" case with a clear message (see how replay / stats do it).