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/components/common/EmptyState.vue

@@ -43,16 +43,7 @@
           @click="!actionTo && $emit('action')"
           class="btn btn-primary"
         >
-          <svg
-            v-if="actionIcon"
-            class="mr-2 h-5 w-5"
-            fill="none"
-            stroke="currentColor"
-            viewBox="0 0 24 24"
-            stroke-width="1.5"
-          >
-            <path stroke-linecap="round" stroke-linejoin="round" d="M12 4.5v15m7.5-7.5h-15" />
-          </svg>
+          <Icon v-if="actionIcon" name="plus" size="md" class="mr-2" />
           {{ actionText }}
         </component>
       </slot>
@@ -64,6 +55,7 @@
 import { computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 import type { Component } from 'vue'
+import Icon from '@/components/icons/Icon.vue'
 
 const { t } = useI18n()