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/App.vue

@@ -38,6 +38,10 @@
         <RouterLink :to="{name: 'customers'}">Telegram Покупатели</RouterLink>
       </li>
 
+      <li :class="{active: route.name === 'pulse'}">
+        <RouterLink :to="{name: 'pulse'}">TeleCart Pulse</RouterLink>
+      </li>
+
       <li :class="{active: route.name === 'logs'}">
         <RouterLink :to="{name: 'logs'}">Журнал событий</RouterLink>
       </li>