feat: add Worlds 2-3, patch persistence, and zoom controls

- World 2 (Filtros): 8 levels teaching filters, resonance, LFO modulation, acid bass
- World 3 (Envelopes): 8 levels teaching VCA, ADSR, pluck, tremolo, full synth lead
- Star-based world unlock system (12 stars for W2, 24 for W3)
- Level patch persistence: auto-saves player patches, restores on revisit
- Google Maps-style zoom controls (+/−/reset) in both puzzle and sandbox views
- Multi-world navigation in GameApp and WorldMap
- Target audio now supports filter chain for World 2 levels

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/game/gameState.js

@@ -1,18 +1,20 @@
 /**
  * gameState.js — Game progress persistence
- * Tracks completed levels, stars earned, and unlocks
+ * Tracks completed levels, stars earned, unlocks, and saved patches per level
  */
 
 const STORAGE_KEY = 'synthquest-progress';
+const PATCHES_KEY = 'synthquest-patches';
 
 const defaultProgress = {
   currentWorld: 'w1',
-  completedLevels: {},  // { levelId: { stars: 3, bestTime: 12.5 } }
+  completedLevels: {},  // { levelId: { stars: 3 } }
   unlockedWorlds: ['w1'],
   totalStars: 0,
 };
 
 let _progress = null;
+let _patches = null; // { levelId: { modules, connections } }
 
 export function loadProgress() {
   if (_progress) return _progress;
@@ -50,15 +52,56 @@ export function getLevelProgress(levelId) {
 
 export function isLevelUnlocked(levelId, worldLevels) {
   const p = loadProgress();
-  // First level is always unlocked
   const idx = worldLevels.findIndex(l => l.id === levelId);
   if (idx === 0) return true;
-  // Previous level must have at least 1 star
   const prevId = worldLevels[idx - 1]?.id;
   return prevId && p.completedLevels[prevId]?.stars >= 1;
 }
 
 export function resetProgress() {
   _progress = { ...defaultProgress };
+  _patches = {};
   saveProgress();
+  savePatches();
+}
+
+// ==================== Level patch persistence ====================
+
+function loadPatches() {
+  if (_patches) return _patches;
+  try {
+    const raw = localStorage.getItem(PATCHES_KEY);
+    _patches = raw ? JSON.parse(raw) : {};
+  } catch {
+    _patches = {};
+  }
+  return _patches;
+}
+
+function savePatches() {
+  if (!_patches) return;
+  try {
+    localStorage.setItem(PATCHES_KEY, JSON.stringify(_patches));
+  } catch {}
+}
+
+export function saveLevelPatch(levelId, modules, connections) {
+  const patches = loadPatches();
+  patches[levelId] = {
+    modules: modules.map(m => ({ id: m.id, type: m.type, x: m.x, y: m.y, params: { ...m.params } })),
+    connections: connections.map(c => ({ ...c })),
+    savedAt: Date.now(),
+  };
+  savePatches();
+}
+
+export function getLevelPatch(levelId) {
+  const patches = loadPatches();
+  return patches[levelId] || null;
+}
+
+export function clearLevelPatch(levelId) {
+  const patches = loadPatches();
+  delete patches[levelId];
+  savePatches();
 }