Add voice selection control

Expose a voice selector next to the save button and pass the choice to TTS so pyttsx3 can prefer a female voice.

client/static/app.js

@@ -1,6 +1,7 @@
 const listEl = document.getElementById("tts-list");
 const textInput = document.getElementById("text-input");
 const saveBtn = document.getElementById("save-btn");
+const voiceSelect = document.getElementById("voice-select");
 const editBtn = document.getElementById("edit-btn");
 const deleteBtn = document.getElementById("delete-btn");
 const cancelBtn = document.getElementById("cancel-btn");
@@ -111,6 +112,7 @@ async function loadList() {
 
 async function handleSave() {
   const text = (textInput.value || "").trim();
+  const voice = (voiceSelect?.value || "male").trim();
   if (text.length < 11) {
     alert("10개 글자 이상이어야 합니다");
     return;
@@ -120,7 +122,7 @@ async function handleSave() {
   const res = await fetch("/api/tts", {
     method: "POST",
     headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ text }),
+    body: JSON.stringify({ text, voice }),
   });
 
   if (!res.ok) {