ui: fixes for kai msg editing

frontend/app/components/Kai/components/ChatLog.tsx

@@ -67,10 +67,10 @@ function ChatLog({
               isUser={msg.isUser}
               userName={userLetter}
               messageId={msg.messageId}
-              isLast={index === lastHumanMsgInd}
               duration={msg.duration}
               feedback={msg.feedback}
               siteId={projectId}
+              canEdit={processingStage === null && msg.isUser && index === lastHumanMsgInd}
             />
           ))}
           {processingStage ? (

frontend/app/components/Kai/components/ChatMsg.tsx

@@ -21,19 +21,19 @@ export function ChatMsg({
   isUser,
   userName,
   messageId,
-  isLast,
   duration,
   feedback,
   siteId,
+  canEdit,
 }: {
   text: string;
   isUser: boolean;
   messageId: string;
   userName?: string;
-  isLast?: boolean;
   duration?: number;
   feedback: boolean | null;
   siteId: string;
+  canEdit?: boolean;
 }) {
   const [isProcessing, setIsProcessing] = React.useState(false);
   const bodyRef = React.useRef<HTMLDivElement>(null);
@@ -103,7 +103,7 @@ export function ChatMsg({
           <Markdown remarkPlugins={[remarkGfm]}>{text}</Markdown>
         </div>
         {isUser ? (
-          isLast ? (
+          canEdit ? (
             <div
               onClick={onRetry}
               className={