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/styles.css

@@ -42,6 +42,21 @@ textarea {
   flex: 1;
 }
 
+.save-row {
+  display: flex;
+  gap: 12px;
+  align-items: center;
+}
+
+.voice-select {
+  border: 1px solid #c9c9c9;
+  border-radius: 4px;
+  padding: 10px 12px;
+  font-size: 14px;
+  background: #ffffff;
+  color: #333;
+}
+
 button {
   border: none;
   padding: 12px 18px;