Add 404 handler

static/Caddyfile

@@ -10,4 +10,12 @@ http://static-mat-services.fly.dev/ {
 :8080 {
   root * /var/www
   file_server
+
+  handle_errors {
+    @404 {
+      expression {http.error.status_code} == 404
+    }
+    rewrite @404 /404.html
+    file_server
+  }
 }