Minor changes

[mwskwong]

1. This can be removed since this is the default value when not specified
   

   mwskwong.com/next.config.mjs

   Line 32 in b11b578

   pathname: '/**',

2. Make SVGR setup more concise. Currently the only usage is the icon.
3. Re-add CSP header

   {
     key: 'Content-Security-Policy',
     value: dedent`
       default-src 'self';
       script-src 'self' 'unsafe-eval' 'unsafe-inline' va.vercel-scripts.com;
       style-src 'self' 'unsafe-inline';
       img-src 'self' images.ctfassets.net blob: data:;
       font-src 'self';
       object-src 'none';
       base-uri 'self';
       form-action 'self';
       frame-ancestors 'none';
       upgrade-insecure-requests;
     `.replace(/\n/g, ''),
   },

4. Remove unused deps
   • clsx
   • @t3-oss/env-core (presets can be accessed via @t3-oss/env-nextjs as well)