Desktop: Compose-for-Desktop app (Stage 3) + folder transcribe script

- desktop/ module compiles the Android app's portable sources directly
  (shared CustomShonarProvider, parsers, folder logic — no copies);
  JVM settings store (0600 JSON) replaces DataStore/Keystore
- Engine screen: spawns the local backend+worker on demand, health-polls,
  auto-provisions a private local account (no login UI)
- Library: folder picker, audio list, report-written badges, search across
  .transcript.md reports; Detail: transcribe with per-file model override,
  job polling, Plaud-style report next to the audio; Settings: model
  registry (default, per-model download)
- scripts/transcribe_folder.py: batch-transcribe a folder via the API
- Reports + shared-parser unit tests green (gradlew test)

.gitignore

@@ -26,6 +26,12 @@ android/app/build/
 *.keystore
 local.properties
 
+# --- Desktop (Compose for Desktop) ---
+desktop/.gradle/
+desktop/.kotlin/
+desktop/build/
+desktop/app/build/
+
 # --- IDE / OS ---
 .idea/
 .vscode/