feat(harvester,jobs): fast gateway harvesting, parallel thread polling, dynamic sidechat spawning

- Implement muse_hybrid fast gateway in response-harvester.py with ThreadPoolExecutor
- Reduce harvest cycle time from ~1m50s to ~18s; eliminate browser tab-hopping and CDP lock contention
- Add smart active thread filtering in get_monitored_threads to prune dead historical test pipes
- Fix initial watermark ingestion logic so fresh sidechats process first-arrival job responses
- Configure gw_wait window in dm.py (20s on reply:expected) so backend generation is not prematurely severed
- Update box-http-health, box-service-health, box-deep-health to dynamic timestamped sidechats without reuse_key
- Fix heartbeat job to route to dedicated heartbeat channel

jobs/box-http-health.json

@@ -15,8 +15,7 @@
   "schedule": "*/15 * * * *",
   "sidechat": {
     "create": true,
-    "name_template": "box-http-health",
-    "reuse_key": "box-http-health"
+    "name_template": "box-http-health-{datetime}"
   },
   "timeout": 600
 }