feat: add SynthQuest game mode with World 1 (Waves) — 8 puzzle levels

Gamified synth learning inspired by Turing Complete. Progressive puzzle
system teaches oscillators, waveforms, frequency, and mixing through
hands-on module patching. Includes world map, level progression with
3-star rating, target audio playback, solution validation, and
localStorage persistence. Sandbox mode still accessible via button.

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

src/game/GameApp.jsx

@@ -0,0 +1,54 @@
+import React, { useState, useCallback } from 'react';
+import WorldMap from './WorldMap.jsx';
+import PuzzleView from './PuzzleView.jsx';
+import { WORLD_1 } from './levels/world1.js';
+
+export default function GameApp({ onSwitchToSandbox }) {
+  const [view, setView] = useState('map'); // 'map' | 'puzzle'
+  const [currentLevel, setCurrentLevel] = useState(null);
+  const [currentLevelIndex, setCurrentLevelIndex] = useState(0);
+
+  const worldLevels = WORLD_1.levels;
+
+  const handleSelectLevel = useCallback((level) => {
+    const idx = worldLevels.findIndex(l => l.id === level.id);
+    setCurrentLevel(level);
+    setCurrentLevelIndex(idx);
+    setView('puzzle');
+  }, [worldLevels]);
+
+  const handleBack = useCallback(() => {
+    setView('map');
+    setCurrentLevel(null);
+  }, []);
+
+  const handleNextLevel = useCallback(() => {
+    const nextIdx = currentLevelIndex + 1;
+    if (nextIdx < worldLevels.length) {
+      setCurrentLevel(worldLevels[nextIdx]);
+      setCurrentLevelIndex(nextIdx);
+    } else {
+      setView('map');
+    }
+  }, [currentLevelIndex, worldLevels]);
+
+  if (view === 'puzzle' && currentLevel) {
+    return (
+      <PuzzleView
+        key={currentLevel.id}
+        level={currentLevel}
+        levelIndex={currentLevelIndex}
+        worldLevels={worldLevels}
+        onBack={handleBack}
+        onNextLevel={handleNextLevel}
+      />
+    );
+  }
+
+  return (
+    <WorldMap
+      onSelectLevel={handleSelectLevel}
+      onSandbox={onSwitchToSandbox}
+    />
+  );
+}