refactor: share human list formatting

src/shared/human-list.ts

@@ -0,0 +1,12 @@
+export function formatHumanList(values: readonly string[]): string {
+  if (values.length === 0) {
+    return "";
+  }
+  if (values.length === 1) {
+    return values[0];
+  }
+  if (values.length === 2) {
+    return `${values[0]} or ${values[1]}`;
+  }
+  return `${values.slice(0, -1).join(", ")}, or ${values.at(-1)}`;
+}