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/lib/stores/settings.ts

@@ -0,0 +1,48 @@
+import { writable } from 'svelte/store';
+import { invoke } from '@tauri-apps/api/core';
+
+export interface AppSettings {
+  ai_provider: string;
+  openai_api_key: string;
+  anthropic_api_key: string;
+  openai_model: string;
+  anthropic_model: string;
+  litellm_model: string;
+  local_model_path: string;
+  local_binary_path: string;
+  transcription_model: string;
+  transcription_device: string;
+  transcription_language: string;
+  skip_diarization: boolean;
+}
+
+const defaults: AppSettings = {
+  ai_provider: 'local',
+  openai_api_key: '',
+  anthropic_api_key: '',
+  openai_model: 'gpt-4o-mini',
+  anthropic_model: 'claude-sonnet-4-6',
+  litellm_model: 'gpt-4o-mini',
+  local_model_path: '',
+  local_binary_path: 'llama-server',
+  transcription_model: 'base',
+  transcription_device: 'cpu',
+  transcription_language: '',
+  skip_diarization: false,
+};
+
+export const settings = writable<AppSettings>({ ...defaults });
+
+export async function loadSettings(): Promise<void> {
+  try {
+    const saved = await invoke<Record<string, unknown>>('load_settings');
+    settings.update(s => ({ ...s, ...saved } as AppSettings));
+  } catch {
+    // Use defaults if settings can't be loaded
+  }
+}
+
+export async function saveSettings(s: AppSettings): Promise<void> {
+  settings.set(s);
+  await invoke('save_settings', { settings: s });
+}