fix(ask): always allow custom select answers

pi-ask-user/test/normalize.test.ts

@@ -2,7 +2,7 @@ import assert from "node:assert/strict";
 import test from "node:test";
 
 import { formatAnswers, normalizeQuestions, orderedAnswers } from "../src/normalize.ts";
-import type { UserAnswer } from "../src/types.ts";
+import type { QuestionInput, UserAnswer } from "../src/types.ts";
 
 test("normalizes select and text questions with bounded defaults", () => {
   const questions = normalizeQuestions([
@@ -27,14 +27,26 @@ test("normalizes select and text questions with bounded defaults", () => {
     prompt: "Choose a language",
     type: "select",
     options: [{ value: "ts", label: "TypeScript" }],
-    allowCustom: true,
     required: true,
   });
   assert.equal(questions[1]?.label, "Q2");
-  assert.equal(questions[1]?.allowCustom, false);
   assert.equal(questions[1]?.required, false);
 });
 
+test("ignores the removed allowCustom input from legacy callers", () => {
+  const legacyQuestion = {
+    id: "language",
+    prompt: "Choose a language",
+    type: "select",
+    options: [{ value: "ts", label: "TypeScript" }],
+    allowCustom: false,
+  } satisfies QuestionInput & { allowCustom: boolean };
+
+  const [question] = normalizeQuestions([legacyQuestion]);
+  assert.ok(question);
+  assert.equal("allowCustom" in question, false);
+});
+
 test("rejects invalid ids, duplicate ids, invalid option combinations, and duplicate values", () => {
   assert.throws(() => normalizeQuestions([{ id: "bad id", prompt: "Bad", type: "text" }]), /must start with a letter/);
   assert.throws(() => normalizeQuestions([null as never]), /must be an object/);