feat: project scaffold — Vite + React + TS + test setup

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

client/src/main.tsx

@@ -0,0 +1,8 @@
+import React from 'react'
+import ReactDOM from 'react-dom/client'
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode>
+    <div>MorseQuest loading...</div>
+  </React.StrictMode>
+)

client/src/test-setup.ts

@@ -0,0 +1,28 @@
+// Mock AudioContext for tests
+class MockAudioContext {
+  currentTime = 0
+  destination = {}
+  state: AudioContextState = 'running'
+  createOscillator() {
+    return {
+      connect: () => {},
+      start: () => {},
+      stop: () => {},
+      frequency: { value: 0 },
+      type: 'sine' as OscillatorType,
+    }
+  }
+  createGain() {
+    return {
+      connect: () => {},
+      gain: {
+        value: 1,
+        setValueAtTime: () => {},
+        linearRampToValueAtTime: () => {},
+      },
+    }
+  }
+  async resume() {}
+  async suspend() {}
+}
+;(global as any).AudioContext = MockAudioContext