Phase 6: Llama-server manager, settings UI, packaging, and polish

- Implement LlamaManager in Rust for llama-server lifecycle: spawn with
  port allocation, health check, clean shutdown on Drop, model listing
- Add llama_start/stop/status/list_models Tauri commands
- Add load_settings/save_settings commands with JSON persistence
- Build SettingsModal with tabs for Transcription, AI Provider, Local AI
  settings (model size, device, language, API keys, provider selection)
- Wire settings into pipeline calls (model, device, language, skip diarization)
- Configure Tauri packaging: asset protocol for local audio files,
  CSP policy, bundle metadata, Linux .deb/.AppImage and Windows .msi config
- Add keyboard shortcuts: Space (play/pause), Ctrl+O (import),
  Ctrl+, (settings), Escape (close menus/modals)
- Close export dropdown on outside click
- Tests: 30 Python, 6 Rust, 0 Svelte errors

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/Cargo.lock

@@ -1498,6 +1498,12 @@ dependencies = [
  "pin-project-lite",
 ]
 
+[[package]]
+name = "http-range"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "21dec9db110f5f872ed9699c3ecf50cf16f423502706ba5c72462e28d3157573"
+
 [[package]]
 name = "httparse"
 version = "1.10.1"
@@ -3595,6 +3601,7 @@ dependencies = [
  "gtk",
  "heck 0.5.0",
  "http",
+ "http-range",
  "jni",
  "libc",
  "log",