feat: sound detection

README.md

@@ -35,7 +35,8 @@ transui             # same as record
 ```
 
 Bind `transui record` to a shortcut in your desktop environment. Transui does
-not register a global shortcut itself.
+not register a global shortcut itself. Recording stops automatically after two
+continuous seconds without detected speech.
 
 The **Hosted first, local fallback** setting tries the Hosted endpoint, then
 the Local endpoint when the first request fails. With it disabled, Transui uses