test(01-01): add failing tests for IndexedDB wrapper

- Tests for openDB with 5 stores, progress CRUD, settings CRUD
- Tests for null return on empty DB
- RED phase: implementation not yet created

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/storage/db.test.ts

@@ -0,0 +1,60 @@
+import "fake-indexeddb/auto";
+import { describe, expect, it, beforeEach } from "vitest";
+import { openDB, getProgress, saveProgress, getSettings, saveSettings } from "./db";
+import type { Progress, Settings } from "../types";
+
+describe("IndexedDB wrapper", () => {
+	let db: IDBDatabase;
+
+	beforeEach(async () => {
+		// Each test gets a fresh database by using a unique name
+		// fake-indexeddb/auto resets between tests in vitest
+		db = await openDB();
+	});
+
+	it("openDB resolves to an IDBDatabase with 5 object store names", () => {
+		const storeNames = Array.from(db.objectStoreNames);
+		expect(storeNames).toHaveLength(5);
+		expect(storeNames).toContain("progress");
+		expect(storeNames).toContain("companionAssets");
+		expect(storeNames).toContain("styleReference");
+		expect(storeNames).toContain("forestElements");
+		expect(storeNames).toContain("settings");
+	});
+
+	it("saveProgress then getProgress returns same data", async () => {
+		const progress: Progress = {
+			id: 1,
+			currentLevel: 1,
+			completedLevels: [],
+			totalSessions: 0,
+			sessionDates: [],
+			selectedCharacter: "fee",
+			selectedLayout: "de",
+		};
+		await saveProgress(db, progress);
+		const result = await getProgress(db);
+		expect(result).toEqual(progress);
+	});
+
+	it("saveSettings then getSettings returns same data", async () => {
+		const settings: Settings = {
+			id: 1,
+			audioEnabled: true,
+			apiKey: "test-key",
+		};
+		await saveSettings(db, settings);
+		const result = await getSettings(db);
+		expect(result).toEqual(settings);
+	});
+
+	it("getProgress on empty DB returns null", async () => {
+		const result = await getProgress(db);
+		expect(result).toBeNull();
+	});
+
+	it("getSettings on empty DB returns null", async () => {
+		const result = await getSettings(db);
+		expect(result).toBeNull();
+	});
+});