fix: ensure API routes are served with correct Content-Type in nginx

- Add specific location block for /api/ routes with application/json Content-Type
- Add .flf extension to cached static assets for font files
- This fixes fonts not loading in production static export

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

nginx.conf

@@ -37,8 +37,15 @@ http {
     add_header X-XSS-Protection "1; mode=block" always;
     add_header Referrer-Policy "no-referrer-when-downgrade" always;
 
+    # API routes - serve as JSON
+    location ~ ^/api/ {
+      add_header Content-Type application/json;
+      add_header Cache-Control "public, max-age=3600";
+      try_files $uri =404;
+    }
+
     # Cache static assets
-    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot|flf)$ {
       expires 1y;
       add_header Cache-Control "public, immutable";
     }