feat: Add TeleCart Pulse heartbeat telemetry

frontend/spa/src/stores/Pulse.js

@@ -1,5 +1,5 @@
 import {defineStore} from "pinia";
-import {ingest, saveTelegramCustomer} from "@/utils/ftch.js";
+import {ingest, saveTelegramCustomer, heartbeat} from "@/utils/ftch.js";
 import {toRaw} from "vue";
 import {deserializeStartParams} from "@/helpers.js";
 
@@ -46,5 +46,11 @@ export const usePulseStore = defineStore('pulse', {
                     .catch(() => console.warn('[Pulse] Failed to save Telegram customer data:', error));
             }
         },
+
+        heartbeat() {
+            heartbeat()
+                .then(() => console.debug('[Pulse] Heartbeat sent'))
+                .catch(err => console.warn('[Pulse] Heartbeat failed:', err));
+        }
     },
 });