feat: 添加navigate.ts以实现可写的currentActivate状态管理

src/lib/stores/navigate.ts

@@ -0,0 +1,5 @@
+import { writable } from "svelte/store";
+
+export type MainFunctions = 'dataset' | 'dataset_settings' | 'pictures' | 'analysis' | 'settings';
+
+export const currentActivate = writable<MainFunctions | null>(null);