feat: add Vercel analytics to website + Play Store review triage script

- docs-site/index.html: add Vercel Analytics + Speed Insights CDN scripts
  (only fires on opencode.agentlabs.cc served via Vercel, not GitHub Pages)
- scripts/triage-reviews.py: fetch recent Play Store reviews via Android
  Publisher API, create GitHub issues for ≤3★ reviews not yet tracked

Run review triage manually on VM:
  DAYS_BACK=7 GOOGLE_SERVICE_ACCOUNT_JSON=... GH_TOKEN=... python3 scripts/triage-reviews.py

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

docs-site/index.html

@@ -9,6 +9,9 @@
 <meta name="theme-color" content="#3b82f6" />
 <link rel="canonical" href="https://dzianisv.github.io/opencode-mobile/" />
 <link rel="icon" type="image/png" href="fdroid/repo/icons/icon.png" />
+<!-- Vercel Web Analytics — privacy-first, no cookies -->
+<script defer src="https://cdn.vercel-insights.com/v1/speed-insights/script.js"></script>
+<script defer src="https://cdn.vercel-insights.com/v1/script.js"></script>
 
 <!-- Open Graph -->
 <meta property="og:type" content="website" />