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/src/commands/system.rs

@@ -1,2 +1,64 @@
-// System commands — hardware detection, llama-server lifecycle
-// TODO: Implement hardware detection and llama-server management
+use serde_json::{json, Value};
+
+use crate::llama::{LlamaConfig, LlamaManager, LlamaStatus};
+
+use std::path::PathBuf;
+use std::sync::OnceLock;
+
+/// Global llama manager — persists across command invocations.
+fn llama_manager() -> &'static LlamaManager {
+    static INSTANCE: OnceLock<LlamaManager> = OnceLock::new();
+    INSTANCE.get_or_init(LlamaManager::new)
+}
+
+/// Start the local llama-server with a GGUF model.
+#[tauri::command]
+pub fn llama_start(
+    model_path: String,
+    binary_path: Option<String>,
+    port: Option<u16>,
+    n_gpu_layers: Option<i32>,
+    context_size: Option<u32>,
+    threads: Option<u32>,
+) -> Result<LlamaStatus, String> {
+    let config = LlamaConfig {
+        binary_path: PathBuf::from(
+            binary_path.unwrap_or_else(|| "llama-server".to_string()),
+        ),
+        model_path: PathBuf::from(model_path),
+        port: port.unwrap_or(0),
+        n_gpu_layers: n_gpu_layers.unwrap_or(0),
+        context_size: context_size.unwrap_or(4096),
+        threads: threads.unwrap_or(4),
+    };
+
+    llama_manager().start(&config)
+}
+
+/// Stop the local llama-server.
+#[tauri::command]
+pub fn llama_stop() -> Result<(), String> {
+    llama_manager().stop()
+}
+
+/// Get the status of the local llama-server.
+#[tauri::command]
+pub fn llama_status() -> LlamaStatus {
+    llama_manager().status()
+}
+
+/// List available GGUF models in the models directory.
+#[tauri::command]
+pub fn llama_list_models() -> Value {
+    let models = LlamaManager::list_models();
+    json!({
+        "models": models,
+        "models_dir": LlamaManager::models_dir().to_string_lossy(),
+    })
+}
+
+/// Get the app data directory path.
+#[tauri::command]
+pub fn get_data_dir() -> String {
+    LlamaManager::data_dir().to_string_lossy().to_string()
+}