feat(web): I1 shell and I2 customer/project UI

Vue 3 + Element Plus layout with JWT login, RBAC routes, axios 401
handling with token restore, and Customers/Projects views wired to
platform APIs.

Made-with: Cursor

web/delivery-platform-ui/src/layout/MainLayout.vue

@@ -0,0 +1,70 @@
+<template>
+  <el-container class="shell">
+    <el-aside width="220px" class="aside">
+      <div class="brand">创飞 · 交付平台</div>
+      <el-menu router :default-active="route.path" background-color="#001529" text-color="#fff" active-text-color="#ffd04b">
+        <el-menu-item index="/">
+          <span>首页</span>
+        </el-menu-item>
+        <el-menu-item index="/customers">
+          <span>客户管理</span>
+        </el-menu-item>
+        <el-menu-item index="/projects">
+          <span>项目管理</span>
+        </el-menu-item>
+      </el-menu>
+    </el-aside>
+    <el-container>
+      <el-header class="top">
+        <span class="user">{{ auth.displayName || "—" }}</span>
+        <el-button type="danger" link @click="logout">退出</el-button>
+      </el-header>
+      <el-main class="main">
+        <router-view />
+      </el-main>
+    </el-container>
+  </el-container>
+</template>
+
+<script setup>
+import { useRoute, useRouter } from "vue-router";
+import { useAuthStore } from "../stores/auth";
+
+const route = useRoute();
+const router = useRouter();
+const auth = useAuthStore();
+
+function logout() {
+  auth.logout();
+  router.push({ name: "login" });
+}
+</script>
+
+<style scoped>
+.shell {
+  height: 100vh;
+}
+.aside {
+  background: #001529;
+  color: #fff;
+}
+.brand {
+  padding: 16px;
+  font-weight: 600;
+  border-bottom: 1px solid #ffffff22;
+}
+.top {
+  display: flex;
+  align-items: center;
+  justify-content: flex-end;
+  gap: 12px;
+  border-bottom: 1px solid #ebeef5;
+}
+.user {
+  color: #606266;
+  font-size: 14px;
+}
+.main {
+  background: #f0f2f5;
+}
+</style>