feat(01-01): implement TypeScript interfaces and IndexedDB wrapper

- All shared interfaces: Progress, Settings, ForestElement, CompanionAssets, etc.
- IndexedDB wrapper with 5 stores (progress, companionAssets, styleReference, forestElements, settings)
- CRUD for progress and settings stores
- 5 passing tests with fake-indexeddb

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

src/types.ts

@@ -0,0 +1,72 @@
+// Companion types
+export type CompanionType = "fee" | "einhorn" | "fuchs" | "eule";
+export type KeyboardLayout = "de" | "ch";
+
+// Level status for the forest map
+export type LevelStatus = "locked" | "current" | "completed";
+
+// Progress store
+export interface Progress {
+	id: 1; // singleton row
+	currentLevel: number;
+	completedLevels: number[];
+	totalSessions: number;
+	sessionDates: string[]; // ISO date strings (days only)
+	selectedCharacter: CompanionType;
+	selectedLayout: KeyboardLayout;
+}
+
+// Companion assets store
+export interface CompanionAssets {
+	characterType: CompanionType;
+	characterSheet: Blob;
+	avatarImage: Blob;
+	generatedAt: string; // ISO date
+}
+
+// Style reference store
+export interface StyleReference {
+	id: 1; // singleton
+	imageBlob: Blob;
+	generatedAt: string;
+}
+
+// Forest element store
+export interface ForestElement {
+	id?: number; // auto-increment
+	levelCompleted: number;
+	imageBlob: Blob;
+	imagePrompt: string;
+	description: string;
+	companionText: string;
+	position: { x: number; y: number };
+	createdAt: string;
+}
+
+// Settings store
+export interface Settings {
+	id: 1; // singleton
+	audioEnabled: boolean;
+	apiKey: string;
+}
+
+// Level definition (used in game/levels.ts)
+export interface Level {
+	level: number;
+	newKeys: string[];
+	allKeys: string[]; // cumulative keys up to this level
+	fingerMap: Record<string, string>; // key -> CSS variable name for finger color
+}
+
+// Typing exercise state
+export interface TypingExerciseState {
+	currentLetterIndex: number;
+	letters: string[];
+	intervalMs: number;
+	correctStreak: number;
+	totalCorrect: number;
+	totalErrors: number;
+}
+
+// Screen names
+export type ScreenName = "welcome" | "forest" | "lesson" | "reward" | "parent";