feat: add preferences store with cookie source and output directory

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/stores/preferences.svelte.ts

@@ -0,0 +1,43 @@
+import { load, Store } from '@tauri-apps/plugin-store';
+import type { CookieSource } from '$lib/bindings/dependencies';
+
+export type { CookieSource };
+
+export interface Preferences {
+  outputDirectory: string;
+  cookieSource: CookieSource;
+}
+
+const DEFAULT_PREFERENCES: Preferences = {
+  outputDirectory: '~/',
+  cookieSource: { type: 'browser', browser: 'firefox' },
+};
+
+let store: Store | null = null;
+
+export const preferences = $state<Preferences>({ ...DEFAULT_PREFERENCES });
+
+export async function loadPreferences(): Promise<void> {
+  store = await load('preferences.json', { autoSave: true });
+  const savedDir = await store.get<string>('outputDirectory');
+  const savedCookie = await store.get<CookieSource>('cookieSource');
+  if (savedDir) preferences.outputDirectory = savedDir;
+  if (savedCookie) preferences.cookieSource = savedCookie;
+}
+
+export async function savePreferences(): Promise<void> {
+  if (!store) return;
+  await store.set('outputDirectory', preferences.outputDirectory);
+  await store.set('cookieSource', preferences.cookieSource);
+  await store.save();
+}
+
+export async function setOutputDirectory(dir: string): Promise<void> {
+  preferences.outputDirectory = dir;
+  await savePreferences();
+}
+
+export async function setCookieSource(source: CookieSource): Promise<void> {
+  preferences.cookieSource = source;
+  await savePreferences();
+}