feat(canvas): Add message input to ChatPanel with Claude integration

- Add textarea input with Enter-to-send functionality to ChatPanel
- Pass sendMessage and isConnected props from AtomizerCanvas
- Add disabled states during thinking/disconnected states
- Use Lucide Send icon for submit button
- Show connection status with Sparkles welcome icon

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

atomizer-dashboard/frontend/src/components/canvas/AtomizerCanvas.tsx

@@ -47,6 +47,7 @@ function CanvasFlow() {
     executeIntent,
     validateIntent,
     analyzeIntent,
+    sendMessage,
   } = useCanvasChat({
     onError: (error) => console.error('Canvas chat error:', error),
   });
@@ -213,6 +214,8 @@ function CanvasFlow() {
           <ChatPanel
             messages={messages}
             isThinking={isThinking || isExecuting}
+            onSendMessage={sendMessage}
+            isConnected={isConnected}
           />
         </div>
       ) : selectedNode ? (

atomizer-dashboard/frontend/src/components/canvas/panels/ChatPanel.tsx

@@ -1,48 +1,96 @@
 /**
- * Chat Panel for Canvas - Displays messages from Claude
+ * Chat Panel for Canvas - Displays messages from Claude with input
  */
 
-import { useRef, useEffect } from 'react';
+import { useRef, useEffect, useState, KeyboardEvent } from 'react';
+import { Send, Sparkles } from 'lucide-react';
 import { Message, ChatMessage } from '../../chat/ChatMessage';
 import { ThinkingIndicator } from '../../chat/ThinkingIndicator';
 
 interface ChatPanelProps {
   messages: Message[];
   isThinking: boolean;
+  onSendMessage?: (message: string) => void;
+  isConnected?: boolean;
 }
 
-export function ChatPanel({ messages, isThinking }: ChatPanelProps) {
+export function ChatPanel({ messages, isThinking, onSendMessage, isConnected = true }: ChatPanelProps) {
   const messagesEndRef = useRef<HTMLDivElement>(null);
+  const [input, setInput] = useState('');
 
   // Auto-scroll to bottom when new messages arrive
   useEffect(() => {
     messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
   }, [messages, isThinking]);
 
+  const handleSend = () => {
+    if (input.trim() && onSendMessage && !isThinking) {
+      onSendMessage(input.trim());
+      setInput('');
+    }
+  };
+
+  const handleKeyDown = (e: KeyboardEvent<HTMLTextAreaElement>) => {
+    if (e.key === 'Enter' && !e.shiftKey) {
+      e.preventDefault();
+      handleSend();
+    }
+  };
+
   return (
-    <div className="flex-1 overflow-y-auto p-4 space-y-4 bg-dark-900">
-      {/* Welcome message if no messages */}
-      {messages.length === 0 && !isThinking && (
-        <div className="text-center py-8">
-          <div className="w-12 h-12 rounded-xl bg-primary-500/20 flex items-center justify-center mx-auto mb-4">
-            <span className="text-2xl">🧠</span>
+    <div className="flex-1 flex flex-col overflow-hidden">
+      {/* Messages */}
+      <div className="flex-1 overflow-y-auto p-4 space-y-4 bg-dark-900">
+        {/* Welcome message if no messages */}
+        {messages.length === 0 && !isThinking && (
+          <div className="text-center py-8">
+            <div className="w-12 h-12 rounded-xl bg-primary-500/20 flex items-center justify-center mx-auto mb-4">
+              <Sparkles size={24} className="text-primary-400" />
+            </div>
+            <p className="text-dark-400 text-sm max-w-xs mx-auto">
+              Use <strong className="text-white">Validate</strong>, <strong className="text-white">Analyze</strong>, or <strong className="text-white">Execute</strong> to interact with Claude about your optimization workflow.
+            </p>
+            <p className="text-dark-500 text-xs mt-4">
+              Or type a message below to ask questions.
+            </p>
+          </div>
+        )}
+
+        {/* Messages */}
+        {messages.map((message) => (
+          <ChatMessage key={message.id} message={message} />
+        ))}
+
+        {/* Thinking indicator */}
+        {isThinking && <ThinkingIndicator />}
+
+        {/* Scroll anchor */}
+        <div ref={messagesEndRef} />
+      </div>
+
+      {/* Input */}
+      {onSendMessage && (
+        <div className="p-3 border-t border-dark-700 bg-dark-850">
+          <div className="flex gap-2">
+            <textarea
+              value={input}
+              onChange={(e) => setInput(e.target.value)}
+              onKeyDown={handleKeyDown}
+              placeholder={isConnected ? "Ask about your optimization..." : "Connecting..."}
+              disabled={isThinking || !isConnected}
+              rows={1}
+              className="flex-1 px-3 py-2 bg-dark-800 border border-dark-600 text-white placeholder-dark-500 rounded-lg resize-none focus:border-primary-500 focus:outline-none transition-colors disabled:opacity-50"
+            />
+            <button
+              onClick={handleSend}
+              disabled={!input.trim() || isThinking || !isConnected}
+              className="px-3 py-2 bg-primary-600 text-white rounded-lg hover:bg-primary-500 disabled:opacity-50 disabled:cursor-not-allowed transition-colors"
+            >
+              <Send size={18} />
+            </button>
           </div>
-          <p className="text-dark-400 text-sm max-w-xs mx-auto">
-            Use <strong className="text-white">Validate</strong>, <strong className="text-white">Analyze</strong>, or <strong className="text-white">Execute</strong> to interact with Claude about your optimization workflow.
-          </p>
         </div>
       )}
-
-      {/* Messages */}
-      {messages.map((message) => (
-        <ChatMessage key={message.id} message={message} />
-      ))}
-
-      {/* Thinking indicator */}
-      {isThinking && <ThinkingIndicator />}
-
-      {/* Scroll anchor */}
-      <div ref={messagesEndRef} />
     </div>
   );
 }