fix: add error handling for CashboxExportScheduler subscription processing

- Wrap runOne(subscription) in try/catch to ensure one subscription failure doesn't block remaining subscriptions
- Log failed subscriptions with new 'cashbox_export_subscription_run_fail' event
- Add new LOGEVENT type for subscription run failures
- Add test to verify second subscription processes even when first fails (continues processing independently)
- All 7 tests passing: 6 original + 1 new failure handling test

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

myteamwallet_backend/src/cashbox-export/cashbox-export.scheduler.ts

@@ -35,7 +35,16 @@ export class CashboxExportScheduler {
     });
 
     for (const subscription of due) {
-      await this.runOne(subscription);
+      try {
+        await this.runOne(subscription);
+      } catch (error) {
+        const errorMessage = error instanceof Error ? error.message : String(error);
+        await this.logger.error({
+          event: 'cashbox_export_subscription_run_fail',
+          details: `recurring subscription failed: subscriptionId=${subscription.id} teamId=${subscription.team.id}: ${errorMessage}`,
+          userId: -1,
+        });
+      }
     }
   }