Add placeholder page flow with localStorage-backed navigation

Four screens (Title, Player Setup, Score Sheet, Enter Scores) wired together
via a simple useState state machine. Auto-resumes to Score Sheet if a game
exists in localStorage under the key 'currentGame'.

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

src/pages/ScoreSheet.tsx

@@ -0,0 +1,14 @@
+interface Props {
+  onScoreRound: () => void
+  onNewGame: () => void
+}
+
+export default function ScoreSheet({ onScoreRound, onNewGame }: Props) {
+  return (
+    <div>
+      <h1>Score Sheet</h1>
+      <button onClick={onScoreRound}>Score Round</button>
+      <button onClick={onNewGame} style={{ fontSize: '0.75em' }}>New Game</button>
+    </div>
+  )
+}