fix(showcase/langgraph-python): restore useDefaultRenderTool() in default catchall cell

The blitz removed the explicit useDefaultRenderTool() call expecting a
framework-level fallback to handle zero-hook registrations, but the
integration uses the published @copilotkit/react-core@1.56.5 which does
not yet ship that fallback. Without the call, useRenderToolCall has no
'*' renderer and tool calls render invisibly — the user only sees the
agent's final text summary instead of the OOTB tool card.

Restore the explicit useDefaultRenderTool() invocation. The framework
fallback (committed in this PR but inert until react-core publishes a
release that includes it) becomes a no-op once that ships.

Author: AlemTuzlak

showcase/integrations/langgraph-python/src/app/demos/tool-rendering-default-catchall/page.tsx

@@ -4,14 +4,25 @@
 //
 // This cell is the simplest point in the three-way progression. The
 // backend exposes a handful of mock tools (get_weather, search_flights,
-// get_stock_price, roll_d20) and the frontend opts into ZERO custom
-// renderers — the runtime's built-in `DefaultToolCallRenderer` paints
-// every tool call with a stable `[data-testid="copilot-tool-render"]`
-// wrapper plus a `data-tool-name="<name>"` attribute.
+// get_stock_price, roll_dice) and the frontend ONLY opts into
+// CopilotKit's built-in default tool-call card — no per-tool renderers,
+// no custom wildcard UI.
+//
+// `useDefaultRenderTool()` (called with no config) registers the built-
+// in `DefaultToolCallRenderer` under the `*` wildcard. That renderer
+// shows the tool name, a live status pill (Running → Done), and a
+// collapsible "Arguments / Result" section that fills in as the call
+// progresses. Without this hook the runtime has NO `*` renderer, so
+// `useRenderToolCall` falls through to `null` and tool calls are
+// invisible — the user only sees the assistant's final text summary.
 
 import React from "react";
-import { CopilotKit, CopilotChat } from "@copilotkit/react-core/v2";
-import { useSuggestions } from "./suggestions";
+import {
+  CopilotKit,
+  CopilotChat,
+  useConfigureSuggestions,
+  useDefaultRenderTool,
+} from "@copilotkit/react-core/v2";
 
 export default function ToolRenderingDefaultCatchallDemo() {
   return (
@@ -30,11 +41,31 @@ export default function ToolRenderingDefaultCatchallDemo() {
 
 function Chat() {
   // @region[default-catchall-zero-config]
-  // The whole point of this cell: ZERO custom render hooks. The
-  // built-in default tool-call renderer paints every tool call.
-  useSuggestions();
+  // Opt in to CopilotKit's built-in default tool-call card. Called with
+  // no config so the package-provided `DefaultToolCallRenderer` is used
+  // as the wildcard renderer — this is the "out-of-the-box" UI the cell
+  // is meant to showcase.
+  useDefaultRenderTool();
   // @endregion[default-catchall-zero-config]
 
+  useConfigureSuggestions({
+    suggestions: [
+      {
+        title: "Weather in SF",
+        message: "What's the weather in San Francisco?",
+      },
+      {
+        title: "Find flights",
+        message: "Find flights from SFO to JFK.",
+      },
+      {
+        title: "Roll a d20",
+        message: "Roll a 20-sided die.",
+      },
+    ],
+    available: "always",
+  });
+
   return (
     <CopilotChat
       agentId="tool-rendering-default-catchall"