fix: repair 4 pre-existing failing tests

- WorkOrderCalcTest: vehicle fixture used `brand` (column is `make`, NOT NULL)
  and WorkOrderPart used `price`/manual total (column is `sell_price`, total is
  auto-computed). Switched to correct columns + valid status.
- ExampleTest: stock test expected 200 on `/` but the central domain redirects
  to /admin. Replaced with a deterministic central-root → /admin redirect check.

Full suite now green: 99 passed, 0 failed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/Feature/WorkOrderCalcTest.php

@@ -50,9 +50,8 @@ class WorkOrderCalcTest extends TestCase
             'work_order_id' => $wo->id,
             'name' => 'Filtru',
             'qty' => 2,
-            'price' => 150,
-            'total' => 300,
-            'status' => 'pending',
+            'sell_price' => 150,
+            'status' => 'needed',
         ]);
 
         $wo->refresh();
@@ -93,7 +92,7 @@ class WorkOrderCalcTest extends TestCase
         $vehicle = Vehicle::create([
             'client_id' => $client->id,
             'plate' => 'TST 001',
-            'brand' => 'Test',
+            'make' => 'Test',
             'model' => 'X',
         ]);