refactor(wel): 重构欢迎页为模块化组件

- 将欢迎页整体结构拆分为多个功能区组件，提高代码可维护性
- 移除原有欢迎横幅、指标卡、图表区、下方区及快捷入口的静态实现
- 引入并注册 SectionKpi、SectionStructure、SectionBusiness 等八个子组件
- 删除冗余样式，更新整体背景和布局样式
- 精简模板内容，仅保留子组件渲染及页脚版权信息
- 移除无用的响应式数据、计算属性及方法
- 包含依赖包 echarts 的新增，支持后续图表功能开发

src/views/wel/components/rank-panel.vue

@@ -0,0 +1,46 @@
+<template>
+  <div class="wel-card rank-panel">
+    <div class="panel-title">
+      {{ title }}
+      <span v-if="unit" class="panel-title__unit">{{ unit }}</span>
+    </div>
+    <wel-chart
+      v-if="type === 'rank'"
+      :option="rankOpt"
+      :height="height"
+    />
+    <wel-chart v-else :option="diffOpt" :height="height" />
+  </div>
+</template>
+
+<script>
+import WelChart from './wel-chart.vue';
+import { rankOption, diffOption } from '../chart-options';
+
+export default {
+  name: 'rank-panel',
+  components: { WelChart },
+  props: {
+    title: { type: String, required: true },
+    unit: { type: String, default: '' },
+    /* rank = 普通排行；diff = 盈亏双向对比 */
+    type: { type: String, default: 'rank' },
+    color: { type: String, default: '#4a90e2' },
+    items: { type: Array, required: true },
+    height: { type: String, default: '300px' },
+    nameWidth: { type: Number, default: 100 },
+  },
+  computed: {
+    rankOpt() {
+      return rankOption(this.items, { color: this.color, unit: this.unit, nameWidth: this.nameWidth });
+    },
+    diffOpt() {
+      return diffOption(this.items);
+    },
+  },
+};
+</script>
+
+<style lang="scss" scoped>
+@import '../dashboard.scss';
+</style>