feat: 商业认证+核算页面重写，管理入口移到用户菜单

商业认证:
- 重写申请表单：认证类型、企业名称、联系电话、业务描述
- 状态栏样式：左侧彩色条（绿/橙/红）
- 用户管理页：同一用户只显示一条，可展开历史查看拒绝原因
- 后端 API 补充 reject_reason 字段

商业核算:
- 成分表改为标准表格（精油/用量/单价/小计）
- 总成本显示栏（绿色背景大字）
- 定价字段放在成本下方

管理入口:
- 操作日志/Bug/用户管理从主 tab 栏移到管理员用户菜单
- 添加配方按钮对所有用户可见

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/views/UserManagement.vue

@@ -22,17 +22,33 @@
     </div>
 
     <!-- Business Application Approval -->
-    <div v-if="businessApps.length > 0" class="review-section">
+    <div v-if="groupedBizApps.length > 0" class="review-section">
       <h4 class="section-title">💼 商业认证申请</h4>
       <div class="review-list">
-        <div v-for="app in businessApps" :key="app._id || app.id" class="review-item">
-          <div class="review-info">
-            <span class="review-name">{{ app.display_name || app.username }}</span>
-            <span class="review-reason">商户名：{{ app.business_name }}</span>
+        <div v-for="group in groupedBizApps" :key="group.user_id" class="biz-app-group">
+          <div class="review-item">
+            <div class="review-info">
+              <span class="review-name">{{ group.latest.display_name || group.latest.username }}</span>
+              <span class="review-reason">商户名：{{ group.latest.business_name }}</span>
+              <span class="biz-status-tag" :class="'biz-' + group.latest.status">{{ { pending: '待审核', approved: '已通过', rejected: '已拒绝' }[group.latest.status] }}</span>
+            </div>
+            <div class="review-actions">
+              <template v-if="group.latest.status === 'pending'">
+                <button class="btn-sm btn-approve" @click="approveBusiness(group.latest)">通过</button>
+                <button class="btn-sm btn-reject" @click="rejectBusiness(group.latest)">拒绝</button>
+              </template>
+              <button v-if="group.history.length > 1" class="btn-sm btn-outline" @click="group.expanded = !group.expanded">
+                {{ group.expanded ? '收起' : `历史 (${group.history.length})` }}
+              </button>
+            </div>
           </div>
-          <div class="review-actions">
-            <button class="btn-sm btn-approve" @click="approveBusiness(app)">通过</button>
-            <button class="btn-sm btn-reject" @click="rejectBusiness(app)">拒绝</button>
+          <div v-if="group.expanded" class="biz-history">
+            <div v-for="app in group.history" :key="app.id" class="biz-history-item">
+              <span class="biz-status-tag small" :class="'biz-' + app.status">{{ { pending: '待审核', approved: '已通过', rejected: '已拒绝' }[app.status] }}</span>
+              <span>{{ app.business_name }}</span>
+              <span v-if="app.reject_reason" class="biz-reject-reason">拒绝原因：{{ app.reject_reason }}</span>
+              <span class="biz-time">{{ formatDate(app.created_at) }}</span>
+            </div>
           </div>
         </div>
       </div>
@@ -111,6 +127,27 @@ const searchQuery = ref('')
 const filterRole = ref('')
 const translations = ref([])
 const businessApps = ref([])
+import { reactive } from 'vue'
+
+const groupedBizApps = computed(() => {
+  const map = {}
+  for (const app of businessApps.value) {
+    const uid = app.user_id
+    if (!map[uid]) map[uid] = { user_id: uid, history: [], latest: null, expanded: false }
+    map[uid].history.push(app)
+  }
+  return Object.values(map).map(g => {
+    g.history.sort((a, b) => b.id - a.id)
+    g.latest = g.history[0]
+    return reactive(g)
+  }).filter(g => g.latest)
+})
+
+function formatDate(d) {
+  if (!d) return ''
+  return new Date(d + 'Z').toLocaleString('zh-CN', { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit' })
+}
+
 const roles = [
   { value: 'admin', label: '管理员' },
   { value: 'senior_editor', label: '高级编辑' },
@@ -138,10 +175,6 @@ function roleLabel(role) {
   return map[role] || role
 }
 
-function formatDate(d) {
-  if (!d) return '--'
-  return new Date(d).toLocaleDateString('zh-CN')
-}
 
 async function loadUsers() {
   try {
@@ -352,8 +385,26 @@ onMounted(() => {
 .review-actions {
   display: flex;
   gap: 6px;
+  flex-shrink: 0;
 }
 
+.biz-app-group { margin-bottom: 6px; }
+.biz-status-tag {
+  font-size: 11px; padding: 2px 8px; border-radius: 8px; font-weight: 500; white-space: nowrap;
+}
+.biz-status-tag.small { font-size: 10px; padding: 1px 6px; }
+.biz-pending { background: #fff3e0; color: #e65100; }
+.biz-approved { background: #e8f5e9; color: #2e7d32; }
+.biz-rejected { background: #fce4ec; color: #c62828; }
+.biz-history {
+  margin: 4px 0 8px 16px; padding: 8px 12px; background: #fafaf8; border-radius: 8px; border-left: 3px solid #e5e4e7;
+}
+.biz-history-item {
+  display: flex; align-items: center; gap: 8px; font-size: 12px; padding: 4px 0; flex-wrap: wrap;
+}
+.biz-reject-reason { color: #c62828; font-size: 11px; }
+.biz-time { color: #bbb; font-size: 11px; margin-left: auto; }
+
 .btn-approve {
   background: #4a9d7e;
   color: #fff;