feat: Report whether a managed host is waiting on a reboot

proto/vantage/v1/vantage.proto

@@ -168,6 +168,9 @@ message InventoryReport {
   uint64 swap_used      = 7;
   repeated PartitionReport partitions = 8;
   string kernel         = 9;
+  // Set on static snapshots only. The agent never reboots; it reports that one
+  // is owed and leaves the decision to a person or a workflow.
+  bool   reboot_required = 10;
 }
 
 message InventoryReportResponse {