fix: persist presets and theme preferences

src/lib/appSettings.ts

@@ -0,0 +1,42 @@
+type ElectronSettingsApi = Pick<Window["electronAPI"], "getAppSetting" | "setAppSetting">;
+
+function getElectronSettingsApi(): ElectronSettingsApi | null {
+	const api = (globalThis as typeof globalThis & { electronAPI?: ElectronSettingsApi })
+		.electronAPI;
+	if (
+		!api ||
+		typeof api.getAppSetting !== "function" ||
+		typeof api.setAppSetting !== "function"
+	) {
+		return null;
+	}
+
+	return api;
+}
+
+export function loadAppSetting<T>(key: string): T | null {
+	const api = getElectronSettingsApi();
+	if (!api) {
+		return null;
+	}
+
+	try {
+		const value = api.getAppSetting(key);
+		return value === undefined ? null : (value as T | null);
+	} catch {
+		return null;
+	}
+}
+
+export function saveAppSetting(key: string, value: unknown): boolean {
+	const api = getElectronSettingsApi();
+	if (!api) {
+		return false;
+	}
+
+	try {
+		return api.setAppSetting(key, value);
+	} catch {
+		return false;
+	}
+}