feat: 登录显示加载遮罩并将统计面板图表改为异步加载

- 登录请求期间显示全屏遮罩与「正在登录」提示，并等待路由跳转完成再隐藏
- 统计面板 echarts 改为 defineAsyncComponent 按需加载，避免阻塞登录后首屏

frontend/src/locales/messages.ts

@@ -56,6 +56,7 @@ export default {
     submit: { zh: '登录', en: 'Sign In', ja: 'ログイン' },
     toRegister: { zh: '没有账号？去注册', en: "Don't have an account? Sign up", ja: 'アカウントをお持ちでない方は新規登録' },
     fillRequired: { zh: '请填写用户名和密码', en: 'Please enter username and password', ja: 'ユーザー名とパスワードを入力してください' },
+    loggingIn: { zh: '正在登录，请稍候…', en: 'Signing in, please wait…', ja: 'ログイン中です。少々お待ちください…' },
     success: { zh: '登录成功', en: 'Signed in successfully', ja: 'ログインしました' },
     failed: { zh: '登录失败', en: 'Sign in failed', ja: 'ログインに失敗しました' },
   },

frontend/src/views/Dashboard.vue

@@ -1,15 +1,10 @@
 <script setup lang="ts">
 // 统计面板组件：展示指定时间范围的收支汇总、概览指标、趋势、分类占比与交易渠道分布
-import { ref, computed, onMounted, watch, nextTick, unref } from 'vue'
+import { ref, computed, onMounted, watch, nextTick, unref, defineAsyncComponent } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { useRouter } from 'vue-router'
 import { NCard, NGrid, NGridItem, NStatistic, NSpace, NSelect, NDatePicker, NInput, NInputNumber, NButton, NAutoComplete, NModal, NAlert, NDropdown, NIcon, useMessage } from 'naive-ui'
 import { SparklesOutline, BulbOutline } from '@vicons/ionicons5'
-import VChart from 'vue-echarts'
-import { use } from 'echarts/core'
-import { CanvasRenderer } from 'echarts/renderers'
-import { LineChart, PieChart, BarChart } from 'echarts/charts'
-import { TitleComponent, TooltipComponent, LegendComponent, GridComponent } from 'echarts/components'
 import { getStatisticsSummary, getStatisticsGroup } from '../api/statistics'
 import { getCategoryList } from '../api/category'
 import { getTagList } from '../api/tag'
@@ -20,8 +15,28 @@ import { useKeywordHistory } from '../composables/useKeywordHistory'
 import { getChannelLabel } from '../utils/channel'
 import { renderCategoryLabel } from '../utils/render'
 
-// 注册 ECharts 所需组件
-use([CanvasRenderer, LineChart, PieChart, BarChart, TitleComponent, TooltipComponent, LegendComponent, GridComponent])
+// 图表组件异步加载：echarts 体积较大，登录后进入面板时先渲染页面骨架，
+// echarts 在后台按需下载并注册，避免阻塞目标页首屏
+const VChart = defineAsyncComponent(async () => {
+  const [vueEcharts, echartsCore, renderers, charts, components] = await Promise.all([
+    import('vue-echarts'),
+    import('echarts/core'),
+    import('echarts/renderers'),
+    import('echarts/charts'),
+    import('echarts/components'),
+  ])
+  echartsCore.use([
+    renderers.CanvasRenderer,
+    charts.LineChart,
+    charts.PieChart,
+    charts.BarChart,
+    components.TitleComponent,
+    components.TooltipComponent,
+    components.LegendComponent,
+    components.GridComponent,
+  ])
+  return vueEcharts.default
+})
 
 const { t, locale } = useI18n() // 国际化
 const message = useMessage() // 消息提示

frontend/src/views/Login.vue

@@ -3,7 +3,7 @@
 import { ref, computed, onMounted } from 'vue'
 import { useRouter, useRoute } from 'vue-router'
 import { useI18n } from 'vue-i18n'
-import { useMessage, NCard, NForm, NFormItem, NInput, NButton, NSpace } from 'naive-ui'
+import { useMessage, NCard, NForm, NFormItem, NInput, NButton, NSpace, NSpin } from 'naive-ui'
 import { login } from '../api/user'
 import { useUserStore } from '../store/user'
 import { useRegistrationStore } from '../store/registration'
@@ -54,7 +54,8 @@ async function handleLogin() {
     userStore.setToken(res.data.token) // 保存 token
     userStore.setUserInfo(res.data.user.nickname, res.data.user.id) // 保存用户信息
     message.success(t('login.success'))
-    router.push(resolveRedirect()) // 跳转到来源页或统计面板
+    // 等待目标页加载完成再隐藏遮罩，避免跳转过程中的空白等待
+    await router.push(resolveRedirect()) // 跳转到来源页或统计面板
   } catch (e: any) {
     message.error(e.message || t('login.failed'))
   } finally {
@@ -82,6 +83,11 @@ async function handleLogin() {
         </NSpace>
       </NForm>
     </NCard>
+    <!-- 登录中遮罩：登录请求已发起，提示用户等待，同时覆盖跳转过程中的加载 -->
+    <div v-if="loading" class="login-loading">
+      <NSpin size="large" stroke="#ffffff" />
+      <span class="login-loading__text">{{ t('login.loggingIn') }}</span>
+    </div>
   </div>
 </template>
 
@@ -93,4 +99,24 @@ async function handleLogin() {
   height: 100vh;
   background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
 }
+
+/* 登录中遮罩：覆盖整个视口，居中显示加载动画与提示文案 */
+.login-loading {
+  position: fixed;
+  inset: 0;
+  z-index: 10;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: 16px;
+  background: rgba(0, 0, 0, 0.35);
+  backdrop-filter: blur(2px);
+}
+
+.login-loading__text {
+  color: #fff;
+  font-size: 14px;
+  letter-spacing: 1px;
+}
 </style>