chore: WebSocket 演示地址切换为 wss://echo.websocket.org（含存量数据迁移）

packages/ui/src/components/editors/WebsocketEditor.tsx

@@ -31,7 +31,7 @@ export function WebsocketEditor({ node }: { node: WebsocketApiNode }) {
         <span className="ops-chip inline-flex items-center gap-1" style={{ padding: "2px 10px" }}><Icon name="zap" size={13} /> WS</span>
         <VarHintInput
           className="ops-input flex-1 font-mono text-[13px]"
-          placeholder="wss://echo.websocket.events"
+          placeholder="wss://echo.websocket.org"
           value={data.url}
           onChange={(v) => patch({ url: v })}
         />

packages/ui/src/workspaceStore.ts

@@ -148,6 +148,15 @@ function sanitizeCollections(collections: Collection[]): Collection[] {
   const fix = (nodes: CollectionNode[]): CollectionNode[] =>
     nodes.map((n) => {
       if (n.type === "folder") return { ...n, children: fix(n.children) };
+      // 一次性迁移：旧演示地址更新为新的公共 echo 服务
+      if (
+        n.type === "request" &&
+        n.kind === "websocket" &&
+        n.data &&
+        (n.data as { url?: string }).url === "wss://echo.websocket.events"
+      ) {
+        (n.data as { url: string }).url = "wss://echo.websocket.org";
+      }
       if (n.type === "request" && (!n.data || !n.kind)) {
         const kind = (n.kind ?? "http") as RequestKind;
         return {