test(mobile): add mobile E2E test suite (53 tests) and fix layout issues

Add comprehensive mobile testing coverage:
- Add chromium-mobile functional test project (iPhone 14, isMobile, hasTouch)
- Add mobile user journey tests (UJ-01/02/04/05/10 mobile variants)
- Add mobile performance baseline tests (FCP/LCP/load time)
- Add mobile accessibility tests (axe-core WCAG 2.1 AA, touch targets,
  form labels, alt text, contrast)
- Update README with progress and new npm scripts

Fix pre-existing issues:
- Fix footer component layout and test assertions
- Fix admin content page sidebar navigation and breadcrumb
- Fix standalone products page metadata and layout
- Fix product detail/service value sections
- Fix contact form layout on mobile
- Fix navigation constants and products data
- Fix layout.tsx CMS config and theme handling
- Fix erp-upgrade content layout

e2e/playwright.config.ts

@@ -90,6 +90,16 @@ export default defineConfig({
       use: { ...devices['Desktop Chrome'] },
       testIgnore: 'visual-regression.spec.ts',
     },
+    {
+      name: 'chromium-mobile',
+      use: {
+        ...devices['iPhone 14'],
+        viewport: { width: 390, height: 844 },
+        isMobile: true,
+        hasTouch: true,
+      },
+      testIgnore: 'visual-regression.spec.ts',
+    },
     {
       name: 'firefox',
       use: { ...devices['Desktop Firefox'] },