fix(device-pool): scope primary key by host and thread through capability_tags

- pooled_devices primary key changed from device_id alone to
  (host_id, device_id), so two hosts reporting the same local
  device_id no longer crash sync_host_devices() with an uncaught
  sqlite3.IntegrityError.
- Device gained a capability_tags field so DevicePool.sync_host_devices()
  can actually populate PooledDevice.capability_tags from a real host
  sync instead of always falling back to an empty list.

openspec: device-pool capability, archived change cloud-runtime

tests/test_console_api.py

@@ -72,6 +72,7 @@ def test_console_status_endpoints_cover_empty_and_populated_states(tmp_path) ->
             "status": "idle",
             "driver_type": "wda",
             "connection_info": {},
+            "capability_tags": [],
         }
     ]
     assert [task["id"] for task in client.get("/console/tasks").json()] == [