feat: auto-trigger reviewer after owner completion with round trip limit

- Owner finishes → auto mark review_ready → reviewer executes
- Reviewer finishes → task back to active → owner can respond
- Automatic ping-pong until consensus or round trip limit
- PAIRED_MAX_ROUND_TRIPS env var (default 10, 0 = unlimited)
- round_trip_count tracked per task in DB

src/message-agent-executor.test.ts

@@ -326,7 +326,7 @@ describe('runAgentForGroup room memory', () => {
         title: null,
         source_ref: 'HEAD',
         review_requested_at: null,
-        plan_notes: null,
+        plan_notes: null, round_trip_count: 0,
         status: 'active',
         created_at: '2026-03-29T00:00:00.000Z',
         updated_at: '2026-03-29T00:00:00.000Z',
@@ -386,7 +386,7 @@ describe('runAgentForGroup room memory', () => {
         reviewer_service_id: 'codex-main',
         title: null,
         source_ref: 'HEAD',
-        plan_notes: null,
+        plan_notes: null, round_trip_count: 0,
         review_requested_at: null,
         status: 'active',
         created_at: '2026-03-28T00:00:00.000Z',
@@ -467,7 +467,7 @@ describe('runAgentForGroup room memory', () => {
         reviewer_service_id: 'claude',
         title: null,
         source_ref: 'HEAD',
-        plan_notes: null,
+        plan_notes: null, round_trip_count: 0,
         review_requested_at: null,
         status: 'active',
         created_at: '2026-03-28T00:00:00.000Z',