Tailwind v4 migration, massive SEO optimization, and fixes

- Migrate to Tailwind CSS v4 with @theme, @layer, @plugin syntax
- Upgrade to Next.js 16.1, React 19.2, TypeScript 5.9.3
- Add 8 technology landing pages (Next.js, React, TypeScript, Tailwind CSS, Claude AI, Python, n8n, KI-Agenten)
- Expand SEO keywords across all locales (de/en/sr) for home, layout, cities, services
- Add tech-specific keywords to all 22 city pages
- Add FAQ schema + seoKeywords to service detail pages
- Add CollectionPage JSON-LD to blog listing
- Fix city page: dynamic region, BASE_URL canonicals, x-default hreflang
- Rewrite terms page with full German AGB, English and Serbian translations
- Remove dead crypto import and unused CSRF middleware (Edge Runtime fix)
- Remove crawlDelay from robots.ts
- Update sitemap with technology pages (~198 indexed URLs)
- Remove deprecated tailwind.config.js

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

playwright.config.ts

@@ -24,8 +24,8 @@ export default defineConfig({
   // Retry on CI only
   retries: process.env.CI ? 2 : 0,
 
-  // Opt out of parallel tests on CI
-  workers: process.env.CI ? 1 : undefined,
+  // Limit workers to avoid overwhelming the dev server
+  workers: process.env.CI ? 1 : 4,
 
   // Reporter to use
   reporter: [
@@ -35,8 +35,8 @@ export default defineConfig({
 
   // Shared settings for all projects
   use: {
-    // Base URL to use in actions like `await page.goto('/')`
-    baseURL: 'http://localhost:3000',
+    // Base URL - uses dedicated test port to avoid conflicts with other dev servers
+    baseURL: 'http://localhost:3100',
 
     // Collect trace when retrying the failed test
     trace: 'on-first-retry',
@@ -45,16 +45,14 @@ export default defineConfig({
     screenshot: 'only-on-failure',
   },
 
-  // Configure projects - Chromium only for Lighthouse compatibility
+  // Configure projects for E2E testing
+  // Note: --remote-debugging-port removed to allow parallel test execution.
+  // For Lighthouse performance tests, use a separate config with a single worker.
   projects: [
     {
       name: 'chromium',
       use: {
         ...devices['Desktop Chrome'],
-        // Launch options for Lighthouse
-        launchOptions: {
-          args: ['--remote-debugging-port=9222'],
-        },
       },
     },
     // Mobile Chrome for responsive testing
@@ -62,9 +60,6 @@ export default defineConfig({
       name: 'mobile-chrome',
       use: {
         ...devices['Pixel 5'],
-        launchOptions: {
-          args: ['--remote-debugging-port=9223'],
-        },
       },
     },
     // Tablet viewport for responsive testing
@@ -72,18 +67,15 @@ export default defineConfig({
       name: 'tablet',
       use: {
         viewport: { width: 768, height: 1024 },
-        launchOptions: {
-          args: ['--remote-debugging-port=9224'],
-        },
       },
     },
   ],
 
-  // Configure web server to start before tests
+  // Configure web server to start before tests on a dedicated port
   webServer: {
-    command: 'npm run dev',
-    url: 'http://localhost:3000',
-    reuseExistingServer: !process.env.CI,
+    command: 'pnpm dev --port 3100',
+    url: 'http://localhost:3100',
+    reuseExistingServer: false,
     timeout: 120000,
   },