fix(ci): add canonical to Playwright web vitals page and regenerate sitemap

The static-docs-checks job failed on two steps:
- Frontmatter & canonical integrity: the new page was missing its
  self-referential trailing-slash `canonical`.
- Sitemap up to date: adding the page to docs.json navigation requires
  regenerating sitemap.xml.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: pirilkavlak

detect/synthetic-monitoring/playwright-checks/performance-metrics.mdx

@@ -3,6 +3,7 @@ title: Performance & Web Vitals
 sidebarTitle: Web Vitals
 description: 'Web Vitals for Playwright Check Suites'
 tags: ['synthetic-monitoring', 'playwright-checks']
+canonical: 'https://www.checklyhq.com/docs/detect/synthetic-monitoring/playwright-checks/performance-metrics/'
 ---
 
 Checkly automatically collects Core Web Vitals for the pages your Playwright Check Suites visit. Every page is measured and scored, and the results appear in the check result. No changes to your tests are needed.

sitemap.xml

@@ -1026,6 +1026,9 @@
   <url>
     <loc>https://www.checklyhq.com/docs/detect/synthetic-monitoring/playwright-checks/overview/</loc>
   </url>
+  <url>
+    <loc>https://www.checklyhq.com/docs/detect/synthetic-monitoring/playwright-checks/performance-metrics/</loc>
+  </url>
   <url>
     <loc>https://www.checklyhq.com/docs/detect/synthetic-monitoring/playwright-checks/quickstart/</loc>
   </url>