feat(feedback): adopt 0–10 recommendation scale (#2438)

* feat(feedback): adopt 10-point recommendation scale

* docs(feedback): keep OSS scale contract self-contained

packages/cli/src/utils/feedbackRating.test.ts

@@ -0,0 +1,17 @@
+import { describe, expect, it } from "vitest";
+
+import { FEEDBACK_RATING_SCALE, parseFeedbackRating } from "./feedbackRating.js";
+
+describe("parseFeedbackRating", () => {
+  it.each(["0", "10"])("accepts the NPS boundary %s", (raw) => {
+    expect(parseFeedbackRating(raw)).toBe(Number(raw));
+  });
+
+  it.each(["-1", "11", "4.5", "10x", ""])("rejects invalid rating %j", (raw) => {
+    expect(parseFeedbackRating(raw)).toBeNull();
+  });
+
+  it("declares the serialized rating scale", () => {
+    expect(FEEDBACK_RATING_SCALE).toBe(10);
+  });
+});