[E4-4] Graceful shutdown incomplete — jsonlWatcher/PipelineManager not stopped

**Finding:** S-1 to S-4 (MEDIUM) | **Milestone:** M-E4: Reliability (#18)

**Problem:** jsonlWatcher, PipelineManager, MemoryBridge not stopped on shutdown.

**Fix:** Call jsonlWatcher.close(), pipelines.destroy(), memoryBridge.stopReaper() in gracefulShutdown(). Await SwarMMonitor.stop with 2s timeout.

**Files:** src/server.ts

**Acceptance:** SIGTERM completes without open file handle warnings.