Add OpenAI chat translation layer

public/admin.js

@@ -79,6 +79,9 @@ $("#adminSoundRepeat").addEventListener("change", (event) => {
 $("#adminSoundTest").addEventListener("click", () => {
   playNotifySound({ ignoreMuted: true });
 });
+$("#translationEnabled").addEventListener("change", saveTranslationSettings);
+$("#operatorLanguage").addEventListener("change", saveTranslationSettings);
+$("#translationModel").addEventListener("change", saveTranslationSettings);
 document.querySelectorAll("[data-settings-tab]").forEach((button) => {
   button.addEventListener("click", () => {
     const tab = button.dataset.settingsTab;
@@ -385,6 +388,21 @@ function renderSite() {
   form.messageBadge.checked = s.notifications?.badgeOnAdminReply !== false;
   form.messageLabel.checked = s.notifications?.labelOnAdminReply !== false;
   form.messageWiggle.checked = s.notifications?.wiggleOnAdminReply !== false;
+  $("#translationEnabled").checked = Boolean(s.translations?.enabled);
+  $("#operatorLanguage").value = s.translations?.operatorLanguage || "cs";
+  $("#translationModel").value = s.translations?.model || "gpt-5.6-luna";
+}
+
+async function saveTranslationSettings() {
+  if (!state.site) return;
+  const settings = structuredClone(state.site.settings);
+  settings.translations = {
+    ...(settings.translations || {}),
+    enabled: $("#translationEnabled").checked,
+    operatorLanguage: $("#operatorLanguage").value,
+    model: $("#translationModel").value.trim() || "gpt-5.6-luna"
+  };
+  await saveSite({ settings, isOnline: state.site.isOnline });
 }
 
 function renderConversations() {
@@ -511,13 +529,28 @@ function renderActive() {
   $("#messages").innerHTML = messages.map((message) => `
     <article class="message ${message.senderType}">
       <div class="by">${escapeHtml(message.senderName || message.senderType)} · ${escapeHtml(message.createdAt)}</div>
-      ${message.body ? `<p>${escapeHtml(message.body)}</p>` : ""}
+      ${renderMessageBody(message)}
       ${renderAttachments(message.attachments)}
     </article>
   `).join("") + adminReadReceipt(conversation, messages);
   $("#messages").scrollTop = $("#messages").scrollHeight;
 }
 
+function renderMessageBody(message) {
+  const original = message.body ? `<p>${escapeHtml(message.body)}</p>` : "";
+  if (!message.translatedBody) return original;
+  const label = message.senderType === "visitor"
+    ? `Preklad do ${escapeHtml(message.translatedLanguage || "")}`
+    : `Odeslano zakaznikovi ${escapeHtml(message.translatedLanguage || "")}`;
+  return `
+    ${original}
+    <div class="translation">
+      <span>${label}</span>
+      <p>${escapeHtml(message.translatedBody)}</p>
+    </div>
+  `;
+}
+
 async function renameVisitor(visitorToken) {
   if (!state.active?.conversation || !visitorToken) return;
   const currentName = conversationVisitorName(state.active.conversation);