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/plugins/README.md

@@ -1,3 +1,16 @@
 # Plugins
 
-Plugins are a way to extend the functionality of your Vue application. Use this folder for registering plugins that you want to use globally.
+`src/plugins` 負責集中註冊全域 Vue plugin。`src/main.ts` 只需要呼叫 `registerPlugins(app)`。
+
+## 目前檔案
+
+- `index.ts`：統一註冊 Vuetify、Pinia、Vue I18n 與 Vue Router。
+- `vuetify.ts`：建立 Vuetify instance，設定 MDI SVG icon set 與預設 theme。
+- `i18n.ts`：建立 Vue I18n instance，載入 `src/language/en-US.json` 與 `src/language/zh-TW.json`。
+
+## 使用規則
+
+- 新增需要 app-wide 安裝的 plugin 時，先建立獨立設定檔，再在 `index.ts` 註冊。
+- 不要在 view 或 component 內重複安裝 plugin。
+- Vuetify theme 設定放在 `src/styles/themes.ts`，不要直接塞在 component。
+- 語系文字放在 `src/language/*.json`，不要散落在 plugin 設定檔。