feat(web): add chat UI with WebSocket streaming and conversation persistence

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/client/src/components/chat/ChatInput.tsx

@@ -0,0 +1,41 @@
+import { useState, useRef } from 'react';
+import { Send } from 'lucide-react';
+import { Button } from '@/components/ui/button';
+
+export function ChatInput({ onSend }: { onSend: (content: string) => void }) {
+  const [input, setInput] = useState('');
+  const ref = useRef<HTMLTextAreaElement>(null);
+
+  const handleSend = () => {
+    if (!input.trim()) return;
+    onSend(input.trim());
+    setInput('');
+    ref.current?.focus();
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === 'Enter' && !e.shiftKey) {
+      e.preventDefault();
+      handleSend();
+    }
+  };
+
+  return (
+    <div className="p-4 border-t border-zinc-800">
+      <div className="flex items-end gap-2 bg-zinc-900 rounded-lg border border-zinc-800 px-3 py-2">
+        <textarea
+          ref={ref}
+          value={input}
+          onChange={(e) => setInput(e.target.value)}
+          onKeyDown={handleKeyDown}
+          rows={1}
+          placeholder="输入指令..."
+          className="flex-1 bg-transparent text-sm resize-none outline-none placeholder:text-zinc-600"
+        />
+        <Button size="icon" variant="ghost" className="h-8 w-8" onClick={handleSend}>
+          <Send size={14} />
+        </Button>
+      </div>
+    </div>
+  );
+}