feat(play): debug retry step, folder hints, and e2e coverage

- Add buildFsAtSubStart so dev "Retry step" resets the current sub while keeping earlier subs complete; quiz screen clears the selected answer.

- Stop adding hinted files' parent folders to click hints (avoids wrongly highlighting Downloads when already inside it).

- Extend Playwright: localStorage reset, full playthrough through quiz, and a retry-step regression test. Add Vitest for buildFsAtSubStart.

Made-with: Cursor

tests/unit/levels.test.ts

@@ -1,12 +1,14 @@
 import { describe, expect, it } from "vitest";
 
 import {
+  buildFsAtSubStart,
   buildInitialFs,
   isFsLevelComplete,
   isQuizComplete,
   isSubComplete,
   QUIZ_CORRECT_ID,
 } from "~/lib/folder-game/levels";
+import { DESKTOP_ID } from "~/lib/folder-game/state";
 
 describe("isFsLevelComplete", () => {
   it("level 0 completes when Games and Documents were opened", () => {
@@ -50,3 +52,33 @@ describe("isQuizComplete", () => {
     expect(isQuizComplete("opt-dl")).toBe(false);
   });
 });
+
+describe("buildFsAtSubStart", () => {
+  it("matches full initial state for sub 0", () => {
+    expect(buildFsAtSubStart(1, 0)).toEqual(buildInitialFs(1));
+  });
+
+  it("level 1 sub 1 start keeps cat sorted and homework on desktop", () => {
+    const fs = buildFsAtSubStart(1, 1);
+    expect(isSubComplete(1, 0, fs)).toBe(true);
+    expect(isSubComplete(1, 1, fs)).toBe(false);
+    const nodes = fs.nodes;
+    const cat = nodes.find((n) => n.id === "file-cat");
+    const hw = nodes.find((n) => n.id === "file-hw");
+    expect(cat?.parentId).toBe("fld-pics");
+    expect(hw?.parentId).toBe(DESKTOP_ID);
+  });
+
+  it("level 2 sub 2 start has beach and budget sorted, installer in downloads", () => {
+    const fs = buildFsAtSubStart(2, 2);
+    const beach = fs.nodes.find((n) => n.id === "f-beach");
+    const budget = fs.nodes.find((n) => n.id === "f-budget");
+    const game = fs.nodes.find((n) => n.id === "f-game");
+    expect(beach?.parentId).toBe("fld-photos");
+    expect(budget?.parentId).toBe("fld-work");
+    expect(game?.parentId).toBe("fld-downloads");
+    expect(isSubComplete(2, 0, fs)).toBe(true);
+    expect(isSubComplete(2, 1, fs)).toBe(true);
+    expect(isSubComplete(2, 2, fs)).toBe(false);
+  });
+});