MeshBeacon: wait out the remaining interval after a reboot (#12274)

* MeshBeacon: wait out the remaining interval after a reboot

When the transmit history shows a beacon inside the interval, runOnce now sleeps until that interval ends instead of a full interval from boot. Saving mesh_beacon reschedules the broadcaster, so enabling broadcast or changing the interval takes effect within the broadcast start delay rather than on the old period.

fixes #12273

* MeshBeacon: retry an airtime-held beacon within the hour

A due beacon held by the air-util limit now rechecks after 5 minutes, doubling to a 60 minute cap, instead of waiting a full interval. The history check runs first, so a beacon that is not due no longer logs a skipped send.

A reschedule requested while runOnce runs, as from the nRF52 BLE write callback, is now kept rather than overwritten by runOnce's return. Declare the transmit_history.dat write in the state manifest.

src/modules/AdminModule.cpp

@@ -1394,8 +1394,10 @@ bool AdminModule::handleSetModuleConfig(const meshtastic_ModuleConfig &c)
         moduleConfig.mesh_beacon = beaconCfg;
         shouldReboot = false;
         // Payload content changed - invalidate the broadcaster's cache.
-        if (meshBeaconBroadcastModule)
+        if (meshBeaconBroadcastModule) {
             meshBeaconBroadcastModule->invalidateCache();
+            meshBeaconBroadcastModule->reschedule();
+        }
         break;
     }
 #endif