Fix false positive test assertions in E2E test suite

[Copilot]

Code review identified 9 test cases with conditional guards that create false positives—tests pass even when expected functionality is missing or broken.

Test Assertion Fixes:

• SEO tests: Require meta description and canonical URL to exist rather than silently skipping validation when absent
• Performance tests: Remove strict wall-clock timing against dev server (varies by machine/CI load) and filter request failures to same-origin only (excludes third-party CDN/transient network issues)
• Locale switching tests: Assert language switcher and navigation links exist/visible before interaction instead of conditional guards
• Navigation tests: Assert contact link visibility before clicking to catch regressions

Example - Before (false positive):

const languageSwitcher = page.locator('[data-locale-switcher]');
if (await languageSwitcher.count() > 0) {
  await languageSwitcher.click();
  await expect(page).toHaveURL(/\/de\//);
}
// Test passes even if switcher is missing

After (proper validation):

const languageSwitcher = page.locator('[data-locale-switcher]');
await expect(languageSwitcher).toBeVisible();
await languageSwitcher.click();
await expect(page).toHaveURL(/\/de\//);
// Test fails if switcher is missing/broken

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.