fix: placement verification and sidechat policy enforcement

- dm.py: placement-aware verify (verify_placement), checked_uuid logging, placement_mismatch events
- main-chat-watchdog.py: P0 alerts on placement_mismatch
- box-ctl.py: notify routes to sidechat, box policy command
- jobs: ops-audit and pipe-demo use sidechats
- response-harvester.py: chain deduplication

Session: sidechat/ops-restore

jobs/pipe-demo-step2.json

@@ -10,5 +10,10 @@
     "nudges": 2,
     "escalate": "opm"
   },
-  "prompt_template": "Pipeline Step 2: Received upstream result from {prev_job_id}:\n\"{prev_result}\"\n\nReview and sign off on the findings.\n\nWhen finished, end your response with:\n[RESULT {job_id}] OK: Step 2 verified and signed off"
+  "prompt_template": "Pipeline Step 2: Received upstream result from {prev_job_id}:\n\"{prev_result}\"\n\nReview and sign off on the findings.\n\nWhen finished, end your response with:\n[RESULT {job_id}] OK: Step 2 verified and signed off",
+  "sidechat": {
+    "create": true,
+    "name_template": "pipe-demo",
+    "reuse_key": "pipe-demo"
+  }
 }