feat(stores): add Pinia domain stores and update docs

Implement concrete Pinia stores for app UI and domain data instead of
placeholder re-exports, including seeded student records and snackbar state.

Refresh README guidance for components, plugins, and services to document the
current project structure, data flow, and usage conventions.feat(stores): add Pinia domain stores and update docs

Implement concrete Pinia stores for app UI and domain data instead of
placeholder re-exports, including seeded student records and snackbar state.

Refresh README guidance for components, plugins, and services to document the
current project structure, data flow, and usage conventions.

src/services/interceptors.ts

@@ -10,7 +10,7 @@ import { tokenService } from './token'
 // 設計重點：
 // - Request：自動注入 token（從 localStorage 讀取）
 //   - 使用 tokenService 作為單一來源，避免 interceptor 直接 import Pinia store 造成循環依賴
-//     store(auth) -> services(userApi) -> httpClient -> interceptors -> store(auth)
+//     store(auth) -> services(authApi/menuApi) -> httpClient -> interceptors -> store(auth)
 // - Response：統一處理 HTTP 錯誤（目前示範 401/403/500）
 //   - 使用 normalizeError 將錯誤轉成 ApiRequestError
 //