refactor(types): introduce Settings and apply in API

- style(prettier): format src files
- style(rustfmt): format Rust sources
- refactor(tauri-api): type-safe getSettings/saveSettings
- refactor(d.ts): declare window.api with Settings

[skip ci]

src/App.tsx

@@ -330,9 +330,7 @@ function App() {
       )}
 
       {isSettingsOpen && (
-        <SettingsModal
-          onClose={() => setIsSettingsOpen(false)}
-        />
+        <SettingsModal onClose={() => setIsSettingsOpen(false)} />
       )}
     </div>
   );