style: 全局 UI 主题皮肤重构与样式模块化

引入 Element Plus 主题定制和主题皮肤 composable，将全局
样式拆分为组件级独立 CSS 文件（侧边栏、顶栏、工作台等），
统一色彩变量和间距规范，重构所有视图和组件样式以适配新
主题系统，优化图表和知识图谱组件视觉表现，提取审计和差
旅报销相关子组件。

web/src/components/shared/EnterpriseSelect.vue

@@ -0,0 +1,72 @@
+<template>
+  <ElSelect
+    class="enterprise-select"
+    popper-class="enterprise-select-popper"
+    :model-value="modelValue"
+    :placeholder="placeholder"
+    :disabled="disabled"
+    :clearable="clearable"
+    :filterable="filterable"
+    :size="size"
+    :teleported="teleported"
+    @change="handleChange"
+  >
+    <ElOption
+      v-for="option in normalizedOptions"
+      :key="option.key"
+      :label="option.label"
+      :value="option.value"
+      :disabled="option.disabled"
+    />
+  </ElSelect>
+</template>
+
+<script setup>
+import { computed } from 'vue'
+
+const props = defineProps({
+  modelValue: { type: [String, Number, Boolean], default: '' },
+  options: { type: Array, required: true },
+  placeholder: { type: String, default: '请选择' },
+  disabled: { type: Boolean, default: false },
+  clearable: { type: Boolean, default: false },
+  filterable: { type: Boolean, default: false },
+  size: { type: String, default: 'default' },
+  teleported: { type: Boolean, default: true }
+})
+
+const emit = defineEmits(['update:modelValue', 'change'])
+
+const normalizedOptions = computed(() =>
+  props.options.map((option, index) => {
+    if (option && typeof option === 'object') {
+      const value = option.value ?? option.label ?? ''
+
+      return {
+        key: `${value}-${index}`,
+        label: String(option.label ?? value),
+        value,
+        disabled: Boolean(option.disabled)
+      }
+    }
+
+    return {
+      key: `${option}-${index}`,
+      label: String(option),
+      value: option,
+      disabled: false
+    }
+  })
+)
+
+function handleChange(value) {
+  emit('update:modelValue', value)
+  emit('change', value)
+}
+</script>
+
+<style scoped>
+.enterprise-select {
+  width: 100%;
+}
+</style>