fix: United claim — add procedure date, fix file attachments, persist chatbot files, enforce M/D/YYYY date parsing

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

apps/Frontend/src/components/layout/chatbot.tsx

@@ -280,12 +280,12 @@ export function ChatbotButton() {
     setBatchClaimData(null);
     setBatchCheckAndClaimData(null);
     setPreauthReadyData(null);
-    setPendingFiles([]);
   };
 
   // Full reset including message history and stored session
   const reset = () => {
     resetStep();
+    setPendingFiles([]);
     const fresh = [makeMsg("bot", "Hi! What can I help you with today?")];
     try {
       sessionStorage.setItem(CHAT_STORAGE_KEY, JSON.stringify(fresh));