fix: flatten customer and user names in project detail response

Frontend expected flat customer_name and responsible_user_name but API
returned nested customers/users objects.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/services/projects.service.ts

@@ -76,9 +76,13 @@ export async function getProject(id: number) {
     },
   });
   if (!project) return null;
-  const { orders, quotations, ...rest } = project;
+  const { orders, quotations, customers, users, ...rest } = project;
   return {
     ...rest,
+    customer_name: customers?.name ?? null,
+    responsible_user_name: users
+      ? `${users.first_name} ${users.last_name}`
+      : null,
     order_number: orders?.order_number ?? null,
     order_status: orders?.status ?? null,
     quotation_number: quotations?.quotation_number ?? null,