feat(pumpingstation): warn when control engages with no machine group registered

A station engaged above startLevel computes a real demand, but if no machine
group is registered (e.g. the Port 2 parent↔group registration was dropped by a
partial redeploy) the demand is silently forwarded nowhere and the pumps never
react — invisible to the operator. levelBased now warns once when engaged with
an empty machineGroups map (throttled via host._warnedNoMachineGroup, re-arms
when a group reappears); manual.forwardDemand warns when neither a group nor a
direct machine is registered.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/control/manual.js

@@ -28,6 +28,18 @@ async function forwardDemand(ctx, demand) {
       }
     }
   }
+
+  // Neither a group nor a direct machine is registered, so the operator's
+  // demand silently goes nowhere. Surface it — the usual cause is a dropped
+  // Port 2 parent↔child registration after a partial redeploy.
+  const noGroups = !machineGroups || Object.keys(machineGroups).length === 0;
+  const noMachines = !machines || Object.keys(machines).length === 0;
+  if (noGroups && noMachines) {
+    logger?.warn?.(
+      `Manual demand ${demand} not forwarded — no machine group or machine is registered to this pumping station. `
+      + `Check the parent↔child Port 2 registration (redeploy/restart fully to restore it).`
+    );
+  }
 }
 
 module.exports = {