feat:mp3 (#3)

---------

Co-authored-by: intelligence <intelligence@debian.local>
Reviewed-on: #3

macos/Sources/Transui/AppModel.swift

@@ -145,8 +145,12 @@ final class AppModel: ObservableObject {
     Task {
       defer { try? FileManager.default.removeItem(at: recording) }
       do {
+        let encoded = try await Task.detached(priority: .userInitiated) {
+          try MP3Encoder.encode(wav: recording)
+        }.value
+        defer { try? FileManager.default.removeItem(at: encoded) }
         let text = try await transcriptionClient.transcribe(
-          recording: recording,
+          recording: encoded,
           plan: transcriptionPlan,
           prompt: settings.prompt
         )