fix: keep footer clear in previews

[Jesssullivan]

Summary

• Increase the page footer's bottom padding so preview/browser bottom chrome no longer covers the final footer line.
• Add a Playwright regression on the CV page at a preview-sized mobile viewport, checking the last visible footer content keeps at least 88px of clearance.

Root cause

The footer content previously had only about 48px of clearance at max scroll. That was visible in a raw browser viewport, but still vulnerable to preview surfaces with their own bottom chrome or overlays.

Validation

• npm run build
• npx playwright test e2e/navigation.spec.ts --project=chromium against npx serve build -l 3000