docs: canonicalize component install URLs

[sanmaxdev]

Summary

• Updated testimonial component pages to use the canonical www registry host in manual install commands.
• Added a Vitest coverage check so component pages do not drift back to the apex registry host.

Verification

• pnpm exec vitest run --config ./vitest.config.mts tests/int/component-docs.int.spec.ts
• pnpm source:build
• pnpm exec tsc --noEmit
• pnpm lint
• git diff --check

Registry Checklist

• public/r output remains out of git.
• No component source, manifest, or installer wiring changes.

Closes #112

[vercel]

@sanmaxdev is attempting to deploy a commit to the ducksss' projects Team on Vercel.

A member of the Team first needs to authorize it.