fix(portal): race-safe owner-seat initialization (firstOrCreate + catch)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/Livewire/Users.php

@@ -4,6 +4,7 @@ namespace App\Livewire;
 
 use App\Models\Customer;
 use App\Models\Seat;
+use Illuminate\Database\UniqueConstraintViolationException;
 use Illuminate\Support\Facades\DB;
 use Livewire\Attributes\Layout;
 use Livewire\Attributes\Validate;
@@ -23,16 +24,19 @@ class Users extends Component
 
     public function mount(): void
     {
-        // Every customer starts with themselves as the owner seat.
+        // Every customer starts with themselves as the owner seat. firstOrCreate
+        // keyed on (customer_id, email) is idempotent; the catch covers the
+        // concurrent-first-visit race against the unique index.
         $customer = $this->customer();
         if ($customer !== null && $customer->seats()->count() === 0) {
-            $customer->seats()->create([
-                'email' => $customer->email,
-                'name' => $customer->name,
-                'role' => 'owner',
-                'status' => 'active',
-                'invited_at' => now(),
-            ]);
+            try {
+                $customer->seats()->firstOrCreate(
+                    ['email' => $customer->email],
+                    ['name' => $customer->name, 'role' => 'owner', 'status' => 'active', 'invited_at' => now()],
+                );
+            } catch (UniqueConstraintViolationException) {
+                // Another concurrent first visit created it — fine.
+            }
         }
     }