fix: make toolInfo.id optional per spec

The spec (apps.mdx) defines toolInfo.id as optional (id?: RequestId),
but the TypeScript types and generated schemas had it as required.

This allows hosts to pass just the tool definition without needing
a request ID, which is useful when the tool name is the primary
information needed by the widget.

src/spec.types.ts

@@ -313,7 +313,7 @@ export interface McpUiHostContext {
   /** @description Metadata of the tool call that instantiated this App. */
   toolInfo?: {
     /** @description JSON-RPC id of the tools/call request. */
-    id: RequestId;
+    id?: RequestId;
     /** @description Tool definition including name, inputSchema, etc. */
     tool: Tool;
   };