adjust templates, add timezone and locale

app/javascript/elements/set_timezone.js

@@ -0,0 +1,7 @@
+export default class extends HTMLElement {
+  connectedCallback () {
+    if (this.dataset.inputId) {
+      document.getElementById(this.dataset.inputId).value = Intl.DateTimeFormat().resolvedOptions().timeZone
+    }
+  }
+}