Implement scoresheet page with scoring logic and confirmation dialog

- Add src/game/scoring.ts with computeRunningTotals and isGameOver
- Build ScoreSheet grid: player columns, per-round scores, running totals after round 2+
- Small red "New Game" button in header top-right with full-screen confirmation overlay
- Extend PageFrame with headerAction and overlay props
- Move press animation/shadow from .pressable class to global button selector

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

src/pages/ScoreSheet.module.css

@@ -0,0 +1,108 @@
+.tableWrapper {
+  overflow-x: auto;
+  -webkit-overflow-scrolling: touch;
+  margin: 0 -1.5rem;
+  padding: 0 1.5rem;
+}
+
+.grid {
+  display: grid;
+  grid-template-columns: 5rem repeat(var(--player-count), 1fr);
+  width: max-content;
+  min-width: 100%;
+}
+
+.headerCell {
+  padding: 0.5rem 0.4rem;
+  font-weight: 600;
+  font-size: 0.8rem;
+  text-align: center;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  border-bottom: 1px solid var(--color-parchment-border);
+}
+
+.labelCell {
+  padding: 0.35rem 0.4rem;
+  font-size: 0.75rem;
+  color: #666;
+  white-space: nowrap;
+}
+
+.scoreCell {
+  padding: 0.35rem 0.4rem;
+  text-align: right;
+  font-size: 0.95rem;
+  font-variant-numeric: tabular-nums;
+}
+
+.totalCell {
+  padding: 0.35rem 0.4rem;
+  text-align: right;
+  font-size: 0.9rem;
+  font-weight: 600;
+  font-variant-numeric: tabular-nums;
+}
+
+.divider {
+  border-top: 1px solid var(--color-parchment-border);
+}
+
+/* Small red "New Game" button in header top-right */
+.newGameBtn {
+  background: #d94f4f;
+  color: white;
+  border: none;
+  border-radius: 0.5rem;
+  font-size: 0.7rem;
+  font-weight: 600;
+  min-height: unset;
+  padding: 0.25rem 0.5rem;
+  line-height: 1.3;
+}
+
+/* Confirmation overlay content */
+.confirmContent {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 1.5rem;
+  padding: 2rem;
+  background: var(--color-parchment);
+  border: 2px solid black;
+  border-radius: 1.5rem;
+  width: calc(100% - 4rem);
+  max-width: 20rem;
+}
+
+.confirmText {
+  margin: 0;
+  font-size: 1.25rem;
+  font-weight: 600;
+}
+
+.confirmButtons {
+  display: flex;
+  gap: 1rem;
+  width: 100%;
+  max-width: 16rem;
+}
+
+.cancelBtn {
+  flex: 1;
+  background: white;
+  border: 2px solid var(--color-parchment-border);
+  border-radius: 0.75rem;
+  font-size: 1rem;
+}
+
+.endGameBtn {
+  flex: 1;
+  background: #d94f4f;
+  color: white;
+  border: none;
+  border-radius: 0.75rem;
+  font-size: 1rem;
+  font-weight: 600;
+}