refactor(cli): dedupe parsePort

src/cli/shared/parse-port.ts

@@ -0,0 +1,19 @@
+export function parsePort(raw: unknown): number | null {
+  if (raw === undefined || raw === null) {
+    return null;
+  }
+  const value =
+    typeof raw === "string"
+      ? raw
+      : typeof raw === "number" || typeof raw === "bigint"
+        ? raw.toString()
+        : null;
+  if (value === null) {
+    return null;
+  }
+  const parsed = Number.parseInt(value, 10);
+  if (!Number.isFinite(parsed) || parsed <= 0) {
+    return null;
+  }
+  return parsed;
+}