refactor: rename platform from 低代码智能体平台 to 天工智能体平台

The platform has evolved from a low-code workflow engine to an autonomous
agent platform with ReAct runtime, multi-agent marketplace, persistent
memory, multimodal tools, and multi-channel integration.

"天工" (Tiangong) draws from 《天工开物》- the wonders of nature and human
ingenuity, reflecting the platform's purpose: empowering users to create
and orchestrate AI agents as masterfully as nature creates all things.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/index.html

@@ -4,7 +4,7 @@
     <meta charset="UTF-8">
     <link rel="icon" href="/favicon.ico">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <title>低代码智能体平台</title>
+    <title>天工智能体平台</title>
   </head>
   <body>
     <div id="app"></div>

frontend/src/components/MainLayout.vue

@@ -3,7 +3,7 @@
     <el-container>
       <el-header>
         <div class="header-content">
-          <h1>低代码智能体平台</h1>
+          <h1>天工智能体平台</h1>
           <div class="header-actions">
             <span v-if="userStore.user">欢迎，{{ userStore.user.username }}</span>
             <el-button @click="handleLogout">退出</el-button>

frontend/src/views/Login.vue

@@ -3,7 +3,7 @@
     <el-card class="login-card">
       <template #header>
         <div class="card-header">
-          <h2>低代码智能体平台</h2>
+          <h2>天工智能体平台</h2>
         </div>
       </template>