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/views/NotFoundView.vue

@@ -0,0 +1,29 @@
+<template>
+  <div class="page">
+    <el-result icon="error" title="404" sub-title="页面不存在">
+      <template #extra>
+        <el-button type="primary" @click="goHome">返回首页</el-button>
+      </template>
+    </el-result>
+  </div>
+</template>
+
+<script setup>
+import { useRouter } from "vue-router";
+
+const router = useRouter();
+
+function goHome() {
+  router.push({ name: "home" });
+}
+</script>
+
+<style scoped>
+.page {
+  min-height: 100vh;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: #f0f2f5;
+}
+</style>