refactor(RouterProvider, chromeStorage, useContextMenuData): 更新存储获取逻辑以移除默认值参数

- 在 RouterProvider 和 useContextMenuData 中更新对 storageUtil.get 的调用，移除默认值参数，简化逻辑。
- 修改 chromeStorage 中的 get 方法签名，确保在没有默认值时返回可选类型，并添加相应的单元测试以验证类型推断。

src/utils/__tests__/chromeStorage.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it } from 'vitest';
+import { describe, expect, it, expectTypeOf } from 'vitest';
 import { storageUtil } from '@/utils/chromeStorage';
 
 describe('chromeStorage', () => {
@@ -75,6 +75,20 @@ describe('chromeStorage', () => {
     });
   });
 
+  describe('get 类型签名', () => {
+    it('无默认值时应推断为可选返回类型', () => {
+      const getWithoutDefault = () => storageUtil.get('app/theme');
+      expectTypeOf<ReturnType<typeof getWithoutDefault>>().toEqualTypeOf<
+        Promise<string | undefined>
+      >();
+    });
+
+    it('有默认值时应推断为确定返回类型', () => {
+      const getWithDefault = () => storageUtil.get('app/theme', 'light');
+      expectTypeOf<ReturnType<typeof getWithDefault>>().toEqualTypeOf<Promise<string>>();
+    });
+  });
+
   describe('set', () => {
     it('应该成功设置字符串值', async () => {
       (chrome.storage.local.set as any).mockResolvedValue(undefined);