feat(admin): add global site settings API, tests and dashboard UI

tests/siteSettings.test.ts

@@ -0,0 +1,33 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import fs from 'node:fs/promises';
+import path from 'node:path';
+
+const DATA_DIR = path.join(process.cwd(), 'app', 'test_data_site_settings');
+const configPath = path.join(DATA_DIR, 'site.config.json');
+
+describe('Global Site Settings API Test', () => {
+  beforeEach(async () => {
+    await fs.mkdir(DATA_DIR, { recursive: true });
+    const dummyConfig = {
+      site_info: { title: 'Alte Firma', phone: '0123456' },
+      navigation: [{ label: 'Home', page_id: 'page_1' }]
+    };
+    await fs.writeFile(configPath, JSON.stringify(dummyConfig, null, 2), 'utf-8');
+  });
+
+  it('soll globale Stammdaten in site.config.json aktualisieren', async () => {
+    const raw = await fs.readFile(configPath, 'utf-8');
+    const config = JSON.parse(raw);
+
+    config.site_info.title = 'N&D IT Solutions GmbH';
+    config.site_info.phone = '+49 7473 123456';
+
+    await fs.writeFile(configPath, JSON.stringify(config, null, 2), 'utf-8');
+
+    const updatedRaw = await fs.readFile(configPath, 'utf-8');
+    const updatedConfig = JSON.parse(updatedRaw);
+
+    expect(updatedConfig.site_info.title).toBe('N&D IT Solutions GmbH');
+    expect(updatedConfig.site_info.phone).toBe('+49 7473 123456');
+  });
+});