Fix nginx 404 handling - return 404 status for missing pages

Changed try_files fallback from /index.html to =404 so that
non-existent pages properly return 404 status and show the
custom 404 error page instead of serving index.html with 200.

nginx.conf

@@ -33,7 +33,8 @@ server {
     location / {
         # Allow nginx to follow symlinks (for web/templates -> ../mbetterclient/qt_player/templates)
         disable_symlinks off;
-        try_files $uri $uri/ /index.html;
+        # Return 404 for missing files instead of falling back to index.html
+        try_files $uri $uri/ =404;
         
         # Cache static assets
         location ~* \.(css|js|jpg|jpeg|png|gif|ico|svg|woff|woff2|ttf|eot)$ {