perf(homepage): reduce artifact JSON escaping

[VrianCao]

What

• Switch homepage preload HTML/SVG attributes to single quotes to reduce JSON escaping in the precomputed render artifact.

Why

• The homepage artifact snapshot stores preload_html inside JSON. Using "-heavy markup increases JSON.stringify cost + snapshot size; single quotes reduce escaping while keeping identical rendered HTML/UX.

Where

• apps/worker/src/snapshots/public-homepage.ts

How to verify

• Local: pnpm lint && pnpm typecheck && pnpm test
• Prod: compare Workers Metrics CPU (homepage refresh + P90) and artifact payload size.