fix: restore arrow key week navigation; improve empty state copy

- WeekNav: add keydown listener for ArrowLeft/ArrowRight week nav
- EmptyState: replace dev-facing "No data scraped yet" + npm commands
  with customer-friendly "Schedule not available yet" message

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

components/EmptyState.tsx

@@ -10,21 +10,11 @@ export function EmptyState() {
       color: "var(--color-text-muted)",
     }}>
       <div style={{ fontSize: "2rem" }}>📅</div>
-      <div style={{ fontSize: "1rem", fontWeight: 600, color: "var(--color-text)" }}>No data scraped yet</div>
+      <div style={{ fontSize: "1rem", fontWeight: 600, color: "var(--color-text)" }}>Schedule not available yet</div>
       <div style={{ fontSize: "0.85rem", textAlign: "center", lineHeight: 1.6 }}>
-        Run the following to populate the calendar:
+        Park hours for this period haven&apos;t been published yet.<br />
+        Check back closer to your visit.
       </div>
-      <pre style={{
-        background: "var(--color-surface)",
-        border: "1px solid var(--color-border)",
-        borderRadius: 8,
-        padding: "12px 20px",
-        fontSize: "0.8rem",
-        color: "var(--color-text)",
-        lineHeight: 1.8,
-      }}>
-        npm run discover{"\n"}npm run scrape
-      </pre>
     </div>
   );
 }