refactor: centralize cli timeout parsing

src/cli/parse-timeout.ts

@@ -0,0 +1,14 @@
+export function parseTimeoutMs(raw: unknown): number | undefined {
+  if (raw === undefined || raw === null) return undefined;
+  let value = Number.NaN;
+  if (typeof raw === "number") {
+    value = raw;
+  } else if (typeof raw === "bigint") {
+    value = Number(raw);
+  } else if (typeof raw === "string") {
+    const trimmed = raw.trim();
+    if (!trimmed) return undefined;
+    value = Number.parseInt(trimmed, 10);
+  }
+  return Number.isFinite(value) ? value : undefined;
+}