feat: add TeleCartPulse telemetry system and ETL endpoints

- Add TeleCartPulse service for event tracking and analytics
  - Implement PayloadSigner for secure payload signing/verification
  - Add StartParamSerializer for campaign parameter handling
  - Create TeleCartPulseServiceProvider for dependency injection
  - Add PulseEvents constants and exception classes

- Add TelemetryHandler for ingesting client-side events
  - Implement /ingest endpoint for receiving webapp events
  - Support WEBAPP_OPEN event tracking with campaign metadata

- Add ETLHandler for customer data export
  - Implement /customers endpoint for ETL processes
  - Add /customers/meta endpoint for pagination metadata
  - Support filtering by updated_at timestamp
  - Include customer metrics: orders count, total spent, etc.

- Add InvalidApiTokenException for API key validation
- Update Request class to support API key extraction
- Add Utils helper methods for domain extraction
- Integrate telemetry in frontend SPA (webapp open event)
- Add TeleCartPulseView in admin panel for API key configuration
- Update routes to include new telemetry and ETL endpoints

frontend/admin/src/router/index.js

@@ -9,6 +9,7 @@ import MainPageView from "@/views/MainPageView.vue";
 import LogsView from "@/views/LogsView.vue";
 import FormBuilderView from "@/views/FormBuilderView.vue";
 import CustomersView from "@/views/CustomersView.vue";
+import TeleCartPulseView from "@/views/TeleCartPulseView.vue";
 
 const router = createRouter({
   history: createMemoryHistory(),
@@ -20,6 +21,7 @@ const router = createRouter({
     {path: '/mainpage', name: 'mainpage', component: MainPageView},
     {path: '/metrics', name: 'metrics', component: MetricsView},
     {path: '/orders', name: 'orders', component: OrdersView},
+    {path: '/pulse', name: 'pulse', component: TeleCartPulseView},
     {path: '/store', name: 'store', component: StoreView},
     {path: '/telegram', name: 'telegram', component: TelegramView},
     {path: '/texts', name: 'texts', component: TextsView},