abbreviateWalletAddress function
Elide an address for prompt display (#383 R3): keeps enough of both ends to visually match against a copied address, short enough that a prompt stays one line. Deterministic, display-only — §5.4: never log the result.
Implementation
String abbreviateWalletAddress(String address) {
final a = address.trim();
if (a.length <= 20) return a;
return '${a.substring(0, 12)}…${a.substring(a.length - 6)}';
}