fix: wallet build failures - BigInt literal and icons

- Replace 0n BigInt literal with BigInt(0) for Safari 13 compatibility
- Generate proper app icons for Windows (.ico) and macOS (.icns)

apps/desktop-wallet/src/pages/Send.tsx

@@ -42,7 +42,7 @@ function parseSynToSompi(amountStr: string): bigint | null {
   const combined = integerPart + decimalPart;
   const result = BigInt(combined);
 
-  return result > 0n ? result : null;
+  return result > BigInt(0) ? result : null;
 }
 
 export default function Send() {