fix(ledger): PayPal import survives a concurrent run of itself

A manual import overlapping the scheduled one could insert the same PayPal
transaction twice and fail on the unique key. The loser now updates the
row the other run created.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/Services/PaymentProvider/PaypalLedgerService.php

@@ -172,7 +172,19 @@ class PaypalLedgerService
             return 'updated';
         }
 
+        try {
             $model::query()->create($row);
+        } catch (\Illuminate\Database\QueryException $e) {
+            // A concurrent import (manual run during the scheduled one) inserted
+            // the same transaction first: update that row instead.
+            $existing = $model::query()->where('stripe_id', $row['stripe_id'])->first();
+            if (! $existing) {
+                throw $e;
+            }
+            $existing->fill($row)->save();
+
+            return 'updated';
+        }
 
         return 'created';
     }