mesh: update node batteryLevel from live NODEINFO_APP packets

battery_level was only populated during the initial sync; NodeInfo
frames streamed as NODEINFO_APP (port 4) now refresh deviceMetrics in
the node database so /api/nodes and downstream consumers see current
values between syncs. decodeNodeInfo + PORT_NODEINFO_APP added to the
codec, one branch in the existing packet-handling path.

src/mesh/mesh.service.ts

@@ -11,6 +11,7 @@ import type { DatabaseSync } from 'node:sqlite';
 import type * as Proto from '@meshtastic/protobufs';
 import {
   BROADCAST_ADDR,
+  PORT_NODEINFO_APP,
   PORT_POSITION_APP,
   PORT_ROUTING_APP,
   PORT_TELEMETRY_APP,
@@ -18,6 +19,7 @@ import {
   buildTextToRadio,
   buildWantConfigToRadio,
   decodeFromRadio,
+  decodeNodeInfo,
   decodePosition,
   decodeRouting,
   decodeTelemetry,
@@ -676,6 +678,23 @@ export class MeshService implements OnModuleInit, OnModuleDestroy {
               position: pos,
             });
           }
+        } else if (decoded && decoded.portnum === PORT_NODEINFO_APP) {
+          // live node-info update: NodeInfo serialized in Data.payload; deviceMetrics carries
+          // battery_level so /api/nodes and the battery alerts see fresh values between syncs
+          let ni: Proto.Mesh.NodeInfo | undefined;
+          try {
+            ni = await decodeNodeInfo(decoded.payload);
+          } catch {
+            ni = undefined; // malformed payload — skip, keep whatever we had
+          }
+          if (ni?.deviceMetrics !== undefined) {
+            const num = pkt.from;
+            this.nodeMap.set(num, {
+              ...this.nodeMap.get(num),
+              num,
+              deviceMetrics: ni.deviceMetrics,
+            });
+          }
         } else if (decoded && decoded.portnum === PORT_ROUTING_APP) {
           // ACK/NACK for our want_ack sends: Routing serialized in Data.payload,
           // Data.requestId = the original packet id we sent