feat: 商业核算+个人库存+认证优化

商业核算:
- 加标语和示意项目（芳香调理），所有人可体验
- 管理员开放（不需认证）
- 新增项目需认证，未认证提示

个人库存:
- 搜索直接添加（回车或点击）
- 4个套装快捷按钮（家庭医生/居家呵护3988/芳香调理/全精油）
- 精油库默认折叠
- 配方匹配排除椰子油，降低门槛（至少1种匹配）

商业认证:
- 简化为商户名+证明图片
- 通过后内容仍显示（和二维码页面一致）
- 审核中内容不可修改

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

frontend/src/views/Projects.vue

@@ -1,12 +1,29 @@
 <template>
   <div class="projects-page">
+    <!-- Header -->
+    <div class="commercial-header">
+      <div class="commercial-icon">💼</div>
+      <div class="commercial-desc">商业用户专属功能，包含项目核算、成本分析等工具</div>
+    </div>
+
     <!-- Project List -->
     <div class="toolbar">
-      <h3 class="page-title">💼 商业核算</h3>
-      <button v-if="auth.isBusiness" class="btn-primary" @click="createProject">+ 新建项目</button>
+      <h3 class="page-title">📊 服务项目成本利润分析</h3>
+      <button class="btn-primary btn-sm" @click="handleCreateProject">+ 新增项目</button>
     </div>
 
     <div v-if="!selectedProject" class="project-list">
+      <!-- Demo project (always visible) -->
+      <div class="project-card demo-card" @click="openDemo">
+        <div class="proj-header">
+          <span class="proj-name">芳香调理（示意）</span>
+          <span class="proj-badge">体验</span>
+        </div>
+        <div class="proj-summary">
+          <span>点击查看示意项目</span>
+        </div>
+      </div>
+      <!-- Real projects -->
       <div
         v-for="p in projects"
         :key="p._id || p.id"
@@ -27,7 +44,6 @@
           <button class="btn-icon-sm" @click="deleteProject(p)" title="删除">🗑️</button>
         </div>
       </div>
-      <div v-if="projects.length === 0" class="empty-hint">暂无项目，点击上方创建</div>
     </div>
 
     <!-- Project Detail -->
@@ -244,6 +260,34 @@ async function loadProjects() {
   }
 }
 
+function handleCreateProject() {
+  if (!auth.isBusiness && !auth.isAdmin) {
+    showCertPrompt()
+    return
+  }
+  createProject()
+}
+
+// Demo project data (local only, per user)
+const demoProject = ref(null)
+function openDemo() {
+  demoProject.value = {
+    _demo: true,
+    name: '芳香调理（示意）',
+    ingredients: [
+      { oil: '芳香调理', drops: 12 },
+      { oil: '椰子油', drops: 186 },
+    ],
+    packaging_cost: 5,
+    labor_cost: 30,
+    other_cost: 10,
+    selling_price: 198,
+    quantity: 1,
+    notes: '这是一个示意项目，您可以修改数字体验功能',
+  }
+  selectedProject.value = demoProject.value
+}
+
 async function createProject() {
   const name = await showPrompt('项目名称:', '新项目')
   if (!name) return
@@ -273,7 +317,7 @@ async function createProject() {
 }
 
 function selectProject(p) {
-  if (!auth.isBusiness) {
+  if (!auth.isBusiness && !auth.isAdmin) {
     showCertPrompt()
     return
   }
@@ -383,6 +427,16 @@ function formatDate(d) {
   padding: 0 12px 24px;
 }
 
+.commercial-header {
+  text-align: center; padding: 24px 16px 16px; margin-bottom: 16px;
+}
+.commercial-icon { font-size: 48px; margin-bottom: 8px; }
+.commercial-desc { font-size: 14px; color: var(--text-light, #999); }
+.demo-card { border-style: dashed !important; opacity: 0.85; }
+.proj-badge {
+  font-size: 10px; background: #fff3e0; color: #e65100; padding: 2px 8px; border-radius: 8px;
+}
+
 .toolbar {
   display: flex;
   align-items: center;