feat(widget): Widget 配置、loader 与右下角悬浮入口

生成可嵌入站点的 loader 与悬浮按钮，支持展开收起和移动端；附独立宿主测试页。

chattermate-test/server.js

@@ -0,0 +1,34 @@
+import express from "express";
+import { fileURLToPath } from "url";
+import { dirname, join } from "path";
+import cors from "cors";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+const app = express();
+const port = process.env.PORT || 3000;
+
+// This server only hosts the test pages. The widget loader is NOT kept here — the
+// pages load it from the frontend origin (vite dev server locally, the dashboard
+// origin in production), exactly like the embed snippet the dashboard generates.
+// A copy in this folder would go stale and silently test an old widget.
+const FRONTEND_ORIGIN = process.env.FRONTEND_ORIGIN || "http://localhost:5173";
+
+// Enable CORS for the widget script
+app.use(cors());
+
+// Serve static files
+app.use(express.static(__dirname));
+
+// Serve index.html
+app.get("/", (req, res) => {
+  res.sendFile(join(__dirname, "index.html"));
+});
+
+app.listen(port, () => {
+  console.log(`Test server running at http://localhost:${port}`);
+  console.log(`UI options gallery:   http://localhost:${port}/ui-options.html`);
+  console.log(`Widget loader from:   ${FRONTEND_ORIGIN}/webclient/chattermate.min.js`);
+  console.log(`(rebuild it after loader changes: cd ../frontend && npm run build:webclient:prod)`);
+});