feat(machine) : add custom field management on machine detail page

- Fix: return customFieldValues in structure endpoint (was hardcoded null)
- Frontend: add editor to create/edit/delete custom field definitions
- Tests: add integration tests for structure values + definition CRUD

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/Api/Controller/MachineStructureCustomFieldValuesTest.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Api\Controller;
+
+use App\Tests\AbstractApiTestCase;
+
+/**
+ * @internal
+ */
+class MachineStructureCustomFieldValuesTest extends AbstractApiTestCase
+{
+    public function testStructureIncludesCustomFieldValues(): void
+    {
+        $machine = $this->createMachine('Machine CFV');
+        $cf      = $this->createCustomField('Tension', 'number', $machine);
+        $this->createCustomFieldValue($cf, '220', $machine);
+
+        $client = $this->createViewerClient();
+        $client->request('GET', sprintf('/api/machines/%s/structure', $machine->getId()));
+
+        $this->assertResponseIsSuccessful();
+        $data = $client->getResponse()->toArray();
+
+        $this->assertArrayHasKey('machine', $data);
+        $this->assertArrayHasKey('customFieldValues', $data['machine']);
+        $this->assertIsArray($data['machine']['customFieldValues']);
+        $this->assertNotEmpty($data['machine']['customFieldValues'], 'customFieldValues should not be empty');
+
+        $cfv = $data['machine']['customFieldValues'][0];
+        $this->assertSame('220', $cfv['value']);
+        $this->assertArrayHasKey('customField', $cfv);
+        $this->assertSame('Tension', $cfv['customField']['name']);
+        $this->assertSame('number', $cfv['customField']['type']);
+    }
+
+    public function testStructureReturnsEmptyArrayWhenNoCustomFieldValues(): void
+    {
+        $machine = $this->createMachine('Machine sans CFV');
+
+        $client = $this->createViewerClient();
+        $client->request('GET', sprintf('/api/machines/%s/structure', $machine->getId()));
+
+        $this->assertResponseIsSuccessful();
+        $data = $client->getResponse()->toArray();
+
+        $this->assertArrayHasKey('customFieldValues', $data['machine']);
+        $this->assertSame([], $data['machine']['customFieldValues']);
+    }
+}