fix(web): consolidate inline currency formatters into shared lib (GOO-205)

Remove 8 inline formatPrice/formatVND/formatPriceM2 functions scattered
across components and pages, replacing them with imports from
@/lib/currency. Add formatVNDFull (full locale, no compact notation) for
chuyen-nhuong pages. Fix price-history-chart off-by-1000 bug caused by
double-dividing through priceToMillions then formatMillions. Add k/m²
branch to formatPricePerM2 for sub-million values.

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

apps/web/components/chuyen-nhuong/transfer-listing-card.tsx

@@ -10,14 +10,12 @@ import {
   CATEGORY_LABELS,
   STATUS_LABELS,
 } from '@/lib/chuyen-nhuong-api';
+import { formatVNDFull } from '@/lib/currency';
 
 interface TransferListingCardProps {
   listing: TransferListingListItem;
 }
 
-function formatVND(value: string): string {
-  return new Intl.NumberFormat('vi-VN').format(Number(value)) + ' \u20ab';
-}
 
 export function TransferListingCard({ listing }: TransferListingCardProps) {
   const statusColor =
@@ -62,7 +60,7 @@ export function TransferListingCard({ listing }: TransferListingCardProps) {
           {/* Price */}
           <div className="mb-3">
             <p className="text-lg font-bold text-primary">
-              {formatVND(listing.askingPriceVND)}
+              {formatVNDFull(listing.askingPriceVND)}
             </p>
             {listing.isNegotiable && (
               <span className="text-xs text-muted-foreground">Thương lượng</span>