feat(cloud): report planner transport status

tests/test_host_agent_internal_api.py

@@ -91,6 +91,19 @@ def test_authenticated_heartbeat_replaces_complete_snapshot(tmp_path) -> None:
     }
 
 
+def test_heartbeat_records_host_planner_transport(tmp_path) -> None:
+    client, pool = _build_client(tmp_path)
+
+    response = client.put(
+        "/internal/v1/hosts/host-a/heartbeat",
+        headers={"Authorization": "Bearer token-a"},
+        json={**_heartbeat_payload("host-a", "device-a"), "planner_transport": "cloud"},
+    )
+
+    assert response.status_code == 200
+    assert pool.store.get_host("host-a").planner_transport == "cloud"  # type: ignore[union-attr]
+
+
 def test_empty_heartbeat_removes_only_reporting_hosts_devices(tmp_path) -> None:
     client, pool = _build_client(tmp_path)
     client.put(