refactor(net): share hostname normalization

src/infra/net/hostname.ts

@@ -0,0 +1,7 @@
+export function normalizeHostname(hostname: string): string {
+  const normalized = hostname.trim().toLowerCase().replace(/\.$/, "");
+  if (normalized.startsWith("[") && normalized.endsWith("]")) {
+    return normalized.slice(1, -1);
+  }
+  return normalized;
+}