refactor(frontend): 完成所有组件的内联SVG统一替换为Icon组件

- 扩展 Icon.vue 组件，新增 60+ 图标路径
  - 导航类: arrowRight, arrowLeft, arrowUp, arrowDown, chevronUp, externalLink
  - 状态类: checkCircle, xCircle, exclamationCircle, exclamationTriangle, infoCircle
  - 用户类: user, userCircle, userPlus, users
  - 文档类: document, clipboard, copy, inbox
  - 操作类: download, upload, filter, sort
  - 安全类: key, lock, shield
  - UI类: menu, calendar, home, terminal, gift, creditCard, mail
  - 数据类: chartBar, trendingUp, database, cube
  - 其他: bolt, sparkles, cloud, server, sun, moon, book 等

- 重构 56 个 Vue 组件，用 Icon 组件替换内联 SVG
  - 净减少约 2200 行代码
  - 提升代码可维护性和一致性
  - 统一图标样式和尺寸管理

frontend/src/views/NotFoundView.vue

@@ -54,35 +54,11 @@
       <!-- Action Buttons -->
       <div class="flex flex-col justify-center gap-3 sm:flex-row">
         <button @click="goBack" class="btn btn-secondary">
-          <svg
-            class="mr-2 h-5 w-5"
-            fill="none"
-            viewBox="0 0 24 24"
-            stroke="currentColor"
-            stroke-width="1.5"
-          >
-            <path
-              stroke-linecap="round"
-              stroke-linejoin="round"
-              d="M10.5 19.5L3 12m0 0l7.5-7.5M3 12h18"
-            />
-          </svg>
+          <Icon name="arrowLeft" size="md" class="mr-2" />
           Go Back
         </button>
         <router-link to="/dashboard" class="btn btn-primary">
-          <svg
-            class="mr-2 h-5 w-5"
-            fill="none"
-            viewBox="0 0 24 24"
-            stroke="currentColor"
-            stroke-width="1.5"
-          >
-            <path
-              stroke-linecap="round"
-              stroke-linejoin="round"
-              d="M2.25 12l8.954-8.955c.44-.439 1.152-.439 1.591 0L21.75 12M4.5 9.75v10.125c0 .621.504 1.125 1.125 1.125H9.75v-4.875c0-.621.504-1.125 1.125-1.125h2.25c.621 0 1.125.504 1.125 1.125V21h4.125c.621 0 1.125-.504 1.125-1.125V9.75M8.25 21h8.25"
-            />
-          </svg>
+          <Icon name="home" size="md" class="mr-2" />
           Go to Dashboard
         </router-link>
       </div>
@@ -104,6 +80,7 @@
 <script setup lang="ts">
 import { useI18n } from 'vue-i18n'
 import { useRouter } from 'vue-router'
+import Icon from '@/components/icons/Icon.vue'
 
 const { t } = useI18n()
 const router = useRouter()