added cors support and started chat client

packages/chat-client/src/App.jsx

@@ -0,0 +1,74 @@
+import React, { useState } from 'react';
+import SessionList from './components/SessionList';
+import ChatWindow from './components/ChatWindow';
+import InfoPanel from './components/InfoPanel';
+import { useSession } from './hooks/useSession';
+import { useChat } from './hooks/useChat';
+
+const DEFAULT_MODEL = 'companion:latest';
+
+export default function App() {
+  const [leftOpen, setLeftOpen] = useState(true);
+  const [rightOpen, setRightOpen] = useState(true);
+  const [selectedModel, setSelectedModel] = useState(DEFAULT_MODEL);
+
+  const {
+    sessions,
+    activeSession,
+    messages,
+    loadingHistory,
+    selectSession,
+    createSession,
+    refreshSessions,
+    appendMessage,
+    updateLastMessage,
+  } = useSession();
+
+  const {
+    sendMessage,
+    cancelStream,
+    streaming,
+    lastTokenCount,
+    lastModel,
+  } = useChat({ activeSession, appendMessage, updateLastMessage, refreshSessions });
+
+  function handleSendMessage(text) {
+    sendMessage(text, selectedModel);
+  }
+
+  return (
+    <div style={{
+      display: 'flex',
+      height: '100vh',
+      overflow: 'hidden',
+    }}>
+      <SessionList
+        sessions={sessions}
+        activeSession={activeSession}
+        onSelectSession={selectSession}
+        onNewChat={createSession}
+        isOpen={leftOpen}
+        onToggle={() => setLeftOpen(o => !o)}
+      />
+
+      <ChatWindow
+        messages={messages}
+        loadingHistory={loadingHistory}
+        streaming={streaming}
+        activeSession={activeSession}
+        onSendMessage={handleSendMessage}
+        onCancel={cancelStream}
+      />
+
+      <InfoPanel
+        isOpen={rightOpen}
+        onToggle={() => setRightOpen(o => !o)}
+        activeSession={activeSession}
+        selectedModel={selectedModel}
+        onModelChange={setSelectedModel}
+        lastModel={lastModel}
+        lastTokenCount={lastTokenCount}
+      />
+    </div>
+  );
+}