feat(csp): add collapseHeaders option to experimental CSP
Adds `collapseHeaders` option to `experimental.csp` that, when used with experimentalStaticHeaders, consolidates all CSP headers into a single catch-all route, preventing build errors and improving performance for large sites with many routes.
- Add collapseHeaders boolean option to experimental.csp configuration
- Modify RouteToHeaders population in generate.ts to support header collapsing
- Add tests for Vercel, Netlify, and Node adapters
- Maintain backward compatibility with existing CSP usage
Benefits all adapters that support experimentalStaticHeaders automatically.
Reduces config file size from MB to KB for large sites.