fix(api): [AB#266] mobile bug fixes — Stripe null guard, audit log, QuickBooks config

JobFlow.API/appsettings.Development.json

@@ -18,5 +18,11 @@
   },
   "Backend": {
     "BaseUrl": "http://localhost:5131"
+  },
+  "QuickBooksSettings": {
+    "ClientId": "YOUR_QB_CLIENT_ID",
+    "ClientSecret": "YOUR_QB_CLIENT_SECRET",
+    "RedirectUrl": "http://localhost:5131/api/quickbooks/callback",
+    "UseSandbox": true
   }
 }

JobFlow.Infrastructure/PaymentGateways/Stripe/StripePaymentProcessor.cs

@@ -103,10 +103,9 @@ public async Task<PaymentSessionResult> CreatePaymentIntentAsync(
                 Destination = request.ConnectedAccountId
             },
 
-            Metadata = new Dictionary<string, string>
-            {
-                { "invoiceId", request.InvoiceId!.Value.ToString() }
-            }
+            Metadata = request.InvoiceId.HasValue
+                ? new Dictionary<string, string> { { "invoiceId", request.InvoiceId.Value.ToString() } }
+                : null
         };
 
         var service = new PaymentIntentService();

JobFlow.Infrastructure/Security/AuditLogService.cs

@@ -95,7 +95,11 @@ orderby a.CreatedAt descending
                 OrganizationName = o != null ? o.OrganizationName : null,
                 OrganizationEmail = o != null ? o.EmailAddress : null,
                 UserId = a.UserId,
-                UserDisplayName = u != null ? (u.FirstName + " " + u.LastName).Trim() : null,
+                UserDisplayName = u != null
+                    ? (u.FirstName != null || u.LastName != null
+                        ? (u.FirstName ?? "") + " " + (u.LastName ?? "")
+                        : u.Email)
+                    : null,
                 Category = a.Category,
                 Action = a.Action,
                 ResourceType = a.ResourceType,