feat(webhooks): enhance Polar webhook processing with proper event handling

- Add support for subscription.uncanceled webhook event
  - Fix spelling mismatch for subscription.canceled (Polar) vs subscription.cancelled (code)
  - Implement proper cancel_at_period_end handling in subscription.canceled events
  - Add cancelled_at field updates for subscription.updated events
  - Handle Polar's spelling variants (canceled_at vs cancelled_at) consistently
  - Remove non-existent pause_reason column from subscription uncanceled handler
  - Enhance webhook logging with detailed field update tracking
  - Add comprehensive cancellation metadata storage in provider_data
  - Gracefully handle null provider_subscription_id in payment confirmation polling

  All Polar webhook events now properly sync subscription state including
  cancellation timing, reasons, and billing period details.

app/Services/Payments/PaymentOrchestrator.php

@@ -1023,7 +1023,7 @@ class PaymentOrchestrator
     /**
      * Check subscription status via provider
      */
-    public function checkSubscriptionStatus(User $user, string $providerName, string $providerSubscriptionId): array
+    public function checkSubscriptionStatus(User $user, string $providerName, ?string $providerSubscriptionId): array
     {
         try {
             $provider = $this->providerRegistry->get($providerName);
@@ -1042,6 +1042,19 @@ class PaymentOrchestrator
                 ];
             }
 
+            if (empty($providerSubscriptionId)) {
+                Log::info('PaymentOrchestrator: Cannot check status - no provider subscription ID', [
+                    'user_id' => $user->id,
+                    'provider' => $providerName,
+                ]);
+
+                return [
+                    'success' => false,
+                    'error' => 'Provider subscription ID not available - webhook may not have processed yet',
+                    'retry_suggested' => true,
+                ];
+            }
+
             Log::info('PaymentOrchestrator: Checking subscription status', [
                 'user_id' => $user->id,
                 'provider' => $providerName,