feat: US-017 - Re-enable boot/login sequence for production

Reverted initial Phase from 'pmr' to 'boot', restoring the full
boot → ECG → login → dashboard flow. All 17 user stories now pass.

src/App.tsx

@@ -44,7 +44,7 @@ function SkipButton({ onSkip }: { onSkip: () => void }) {
 }
 
 function App() {
-  const [phase, setPhase] = useState<Phase>('pmr')
+  const [phase, setPhase] = useState<Phase>('boot')
   const cursorPositionRef = useRef<{ x: number; y: number } | null>(null)
 
   const skipToLogin = () => setPhase('login')