Add admin panel with CRUD endpoints and management UI

Add admin API endpoints for games, routes, pokemon, and route encounters
with full CRUD operations including bulk import. Build admin frontend
with game/route/pokemon management pages, navigation, and data tables.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/components/Layout.tsx

@@ -24,6 +24,12 @@ export function Layout() {
               >
                 My Runs
               </Link>
+              <Link
+                to="/admin"
+                className="px-3 py-2 rounded-md text-sm font-medium hover:bg-gray-100 dark:hover:bg-gray-700"
+              >
+                Admin
+              </Link>
             </div>
           </div>
         </div>