feat(admissions): add admissions guide page and homepage countdown strip

- New /admissions route with AdmissionsView client component
- Live countdowns (days until) to Primary/Secondary deadlines and Offer Days
- Step-by-step timelines for both tracks with highlighted milestone rows
- Tips section covering equal preference rule, late applications, waiting lists
- Homepage countdown strip (4 cards) between discovery chips and how-it-works
- Admissions nav link and footer link added

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

nextjs-app/components/Navigation.tsx

@@ -59,6 +59,12 @@ export function Navigation() {
           >
             Rankings
           </Link>
+          <Link
+            href="/admissions"
+            className={isActive('/admissions') ? `${styles.navLink} ${styles.active}` : styles.navLink}
+          >
+            Admissions
+          </Link>
         </nav>
       </div>
     </header>