Improve invoice verification caching with conflict resolution and error handling

Implement unique constraint on invoice verification cache key and handle duplicate entries gracefully in the backend.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: d43bd811-9372-45a7-8ac9-4a954c0538e1
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/d43bd811-9372-45a7-8ac9-4a954c0538e1/g5c0JYM

server/invoiceVerification.ts

@@ -64,6 +64,11 @@ export class InvoiceVerificationService {
       
       console.log('💾 Résultat sauvé en cache:', { invoiceReference, groupId, exists: result.exists });
     } catch (error) {
+      // Gérer spécifiquement les erreurs de contrainte unique (duplicate key)
+      if (error && typeof error === 'object' && 'code' in error && error.code === '23505') {
+        console.log('🔄 Cache déjà existant pour cette clé, ignoré:', { invoiceReference, groupId });
+        return;
+      }
       console.error('❌ Erreur sauvegarde cache:', error);
     }
   }