perf: add cache headers for static assets on Cloudflare Pages

- Hashed JS/CSS bundles: immutable, 1 year cache
- Images/logos/SVGs: 1 week cache with 1 day stale-while-revalidate
- HTML pages: browser revalidates, CDN caches 1h
- ZIP downloads: 1h cache
- API routes: unchanged (CDN 24h)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/build.js

@@ -245,6 +245,45 @@ function generateCFConfig(buildDir) {
   X-Content-Type-Options: nosniff
   X-Frame-Options: DENY
 
+# HTML pages: browser always revalidates, CDN caches 1h
+/*.html
+  Cache-Control: public, max-age=0, s-maxage=3600, stale-while-revalidate=600
+
+# Hashed JS/CSS bundles: immutable (filename changes on content change)
+/assets/*.js
+  Cache-Control: public, max-age=31536000, immutable
+
+/assets/*.css
+  Cache-Control: public, max-age=31536000, immutable
+
+# Static images and logos: 1 week + 1 day stale
+/assets/*.png
+  Cache-Control: public, max-age=604800, stale-while-revalidate=86400
+
+/assets/*.svg
+  Cache-Control: public, max-age=604800, stale-while-revalidate=86400
+
+/assets/*.webp
+  Cache-Control: public, max-age=604800, stale-while-revalidate=86400
+
+/antipattern-images/*
+  Cache-Control: public, max-age=604800, stale-while-revalidate=86400
+
+# Root static assets (favicon, og-image, etc.)
+/favicon.svg
+  Cache-Control: public, max-age=604800, stale-while-revalidate=86400
+
+/og-image.jpg
+  Cache-Control: public, max-age=604800, stale-while-revalidate=86400
+
+/apple-touch-icon.png
+  Cache-Control: public, max-age=604800, stale-while-revalidate=86400
+
+# ZIP downloads: 1h cache
+/dist/*.zip
+  Cache-Control: public, max-age=3600, stale-while-revalidate=600
+
+# API routes: CDN caches 24h
 /api/*
   Cache-Control: public, s-maxage=86400, stale-while-revalidate=3600