feat: enhance purchase intentions with chat integration and offer tracking

- Added MongoDB chat/message integration for seller responses
- Improved seller response validation and default messaging
- Integrated automatic chat creation/update when responding to intentions
- Added highest custom offer fields to listing queries and models
- Enhanced listing data with top offer information for buyers

components/marketplace/IntentionDetailModal.tsx

@@ -35,6 +35,9 @@ interface PurchaseIntention {
   buyer_message: string | null;
   seller_response: string | null;
   created_at: string;
+  custom_offer_amount: number | null;
+  custom_offer_currency: string | null;
+  custom_offer_created_at: string | null;
   buyer?: {
     user_id: number;
     username: string;
@@ -93,6 +96,40 @@ function getStatusBadge(status: string) {
   }
 }
 
+function formatCustomOffer(intention: PurchaseIntention): { value: string; date: string | null } | null {
+  if (
+    intention.custom_offer_amount === null ||
+    intention.custom_offer_amount === undefined ||
+    !intention.custom_offer_currency
+  ) {
+    return null;
+  }
+
+  const amount = intention.custom_offer_amount;
+  let value: string;
+
+  switch (intention.custom_offer_currency) {
+    case "pix":
+      value = `R$ ${amount.toFixed(2)}`;
+      break;
+    case "tibia_coins":
+      value = `${Math.round(amount).toLocaleString("pt-BR")} TC`;
+      break;
+    case "gold_coins":
+      value = `${Math.round(amount).toLocaleString("pt-BR")} GP`;
+      break;
+    default:
+      value = amount.toLocaleString("pt-BR");
+  }
+
+  return {
+    value,
+    date: intention.custom_offer_created_at
+      ? new Date(intention.custom_offer_created_at).toLocaleString("pt-BR")
+      : null,
+  };
+}
+
 export function IntentionDetailModal({
   open,
   onOpenChange,
@@ -126,6 +163,13 @@ export function IntentionDetailModal({
   const isOwner = user && listing && user.userId === listing.seller_id;
   const canMarkAsSold = isOwner && listing && (listing.listing_status === "active" || listing.listing_status === "in_escrow");
   const canAcceptOrReject = intention.status === "pending";
+  const customOffer = formatCustomOffer(intention);
+
+  useEffect(() => {
+    if (open) {
+      setSellerResponse(intention.seller_response ?? "");
+    }
+  }, [open, intention.intention_id, intention.seller_response]);
 
   const handleAccept = async () => {
     setLoading(true);
@@ -279,6 +323,18 @@ export function IntentionDetailModal({
               </div>
             </div>
 
+            {customOffer && (
+              <div className="bg-primary/5 border border-primary/20 rounded-lg p-3 space-y-1">
+                <Label className="text-xs text-primary uppercase tracking-wide">
+                  Oferta do Comprador
+                </Label>
+                <div className="text-base font-semibold text-primary">{customOffer.value}</div>
+                {customOffer.date && (
+                  <p className="text-[11px] text-primary/70">Enviada em {customOffer.date}</p>
+                )}
+              </div>
+            )}
+
             {/* Mensagem do comprador */}
             {intention.buyer_message && (
               <div>