feat(ui): remove tool selection chips from below input area

ConfigPanel (model mode + tool group chips) is no longer rendered in
the chat layout. Tool selection was surfaced below the input after the
previous refactor but users found it visually noisy. activeTools still
drives tool filtering on submit; UI selection can be re-exposed later
via a dedicated settings entry point.

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

langgraph/src/main.tsx

@@ -19,7 +19,6 @@ import { useConversation } from "@/hooks/useConversation";
 import { useConfig } from "@/hooks/useConfig";
 import { ChatMessages } from "@/components/ChatMessages";
 import { ChatInput } from "@/components/ChatInput";
-import { ConfigPanel } from "@/components/ConfigPanel";
 
 const LANGGRAPH_URL =
   import.meta.env.VITE_LANGGRAPH_URL ?? "http://localhost:2024";
@@ -34,7 +33,7 @@ function App() {
   const [showScrollBtn, setShowScrollBtn] = useState(false);
   const isComposingRef = useRef(false);
 
-  const { activeTools, setActiveTools, modelMode, setModelMode, toggleTool } = useConfig();
+  const { activeTools, modelMode } = useConfig();
 
   const {
     threads, setThreads,
@@ -55,8 +54,6 @@ function App() {
   // Source label from card action buttons
   const [sourceLabel, setSourceLabel] = useState<string | null>(null);
 
-  const configPanelRef = useRef<HTMLDivElement>(null);
-
   // Pending retry tool name
   const pendingRetryToolRef = useRef<string | null>(null);
 
@@ -406,17 +403,6 @@ function App() {
             resetLoading={resetLoading}
           />
 
-          {/* Config panel */}
-          <ConfigPanel
-            configPanelRef={configPanelRef}
-            modelMode={modelMode}
-            setModelMode={setModelMode}
-            activeTools={activeTools}
-            setActiveTools={setActiveTools}
-            toggleTool={toggleTool}
-            activeMessages={activeMessages}
-          />
-
           {/* Stream status bar */}
           {concurrentStatus !== "idle" && (
             <div className="max-w-3xl mx-auto w-full px-5 mb-1">