Documented the transcription bitrate decisions and hardened its fallback

app/MindWork AI Studio/Settings/DataModel/TranscriptionOpusBitrate.cs

@@ -2,8 +2,13 @@ namespace AIStudio.Settings.DataModel;
 
 public enum TranscriptionOpusBitrate
 {
+    // The recommended bitrate is deliberately the member with the underlying value 0: when the
+    // settings file holds a value TolerantEnumConverter cannot read, it falls back to that member.
+    // Landing on the lowest bitrate there would silently reintroduce the very defect this setting
+    // exists to prevent -- transcripts losing what was said quietly.
+    KBPS_128 = 0,
+
     KBPS_32,
     KBPS_64,
-    KBPS_128,
     KBPS_256,
-}
+}