Add prev/next and dropdown route navigation to route detail page

Reduces navigation depth when working with route encounters by adding
prev/next buttons and a route dropdown selector to AdminRouteDetail.

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

frontend/src/pages/admin/AdminRouteDetail.tsx

@@ -1,5 +1,5 @@
-import { useState } from 'react'
-import { useParams, Link } from 'react-router-dom'
+import { useMemo, useState } from 'react'
+import { useParams, Link, useNavigate } from 'react-router-dom'
 import { AdminTable, type Column } from '../../components/admin/AdminTable'
 import { RouteEncounterFormModal } from '../../components/admin/RouteEncounterFormModal'
 import { useGame, useRoutePokemon } from '../../hooks/useGames'
@@ -18,6 +18,7 @@ export function AdminRouteDetail() {
   const { gameId, routeId } = useParams<{ gameId: string; routeId: string }>()
   const gId = Number(gameId)
   const rId = Number(routeId)
+  const navigate = useNavigate()
 
   const { data: game } = useGame(gId)
   const { data: encounters = [], isLoading } = useRoutePokemon(rId, gId)
@@ -29,7 +30,17 @@ export function AdminRouteDetail() {
   const [showCreate, setShowCreate] = useState(false)
   const [editing, setEditing] = useState<RouteEncounterDetail | null>(null)
 
-  const route = game?.routes?.find((r) => r.id === rId)
+  const sortedRoutes = useMemo(
+    () => [...(game?.routes ?? [])].sort((a, b) => a.order - b.order),
+    [game?.routes],
+  )
+  const currentIndex = sortedRoutes.findIndex((r) => r.id === rId)
+  const route = currentIndex >= 0 ? sortedRoutes[currentIndex] : undefined
+  const prevRoute = currentIndex > 0 ? sortedRoutes[currentIndex - 1] : undefined
+  const nextRoute =
+    currentIndex >= 0 && currentIndex < sortedRoutes.length - 1
+      ? sortedRoutes[currentIndex + 1]
+      : undefined
 
   const columns: Column<RouteEncounterDetail>[] = [
     {
@@ -65,15 +76,53 @@ export function AdminRouteDetail() {
           {game?.name ?? '...'}
         </Link>
         {' / '}
-        <span className="text-gray-900 dark:text-gray-100">
-          {route?.name ?? '...'}
-        </span>
+        <select
+          className="text-gray-900 dark:text-gray-100 bg-transparent font-medium cursor-pointer hover:underline border-none p-0 text-sm"
+          value={rId}
+          onChange={(e) => navigate(`/admin/games/${gId}/routes/${e.target.value}`)}
+        >
+          {sortedRoutes.map((r) => (
+            <option key={r.id} value={r.id}>
+              {r.name}
+            </option>
+          ))}
+        </select>
       </nav>
 
       <div className="flex justify-between items-center mb-4">
-        <h2 className="text-xl font-semibold">
-          {route?.name ?? 'Route'} - Pokemon ({encounters.length})
-        </h2>
+        <div className="flex items-center gap-2">
+          <h2 className="text-xl font-semibold">
+            {route?.name ?? 'Route'} - Pokemon ({encounters.length})
+          </h2>
+          <div className="flex items-center gap-1 ml-2">
+            {prevRoute ? (
+              <Link
+                to={`/admin/games/${gId}/routes/${prevRoute.id}`}
+                className="px-2 py-1 text-sm rounded border border-gray-300 dark:border-gray-600 hover:bg-gray-100 dark:hover:bg-gray-700"
+                title={prevRoute.name}
+              >
+                &larr; Prev
+              </Link>
+            ) : (
+              <span className="px-2 py-1 text-sm rounded border border-gray-200 dark:border-gray-700 text-gray-300 dark:text-gray-600 cursor-not-allowed">
+                &larr; Prev
+              </span>
+            )}
+            {nextRoute ? (
+              <Link
+                to={`/admin/games/${gId}/routes/${nextRoute.id}`}
+                className="px-2 py-1 text-sm rounded border border-gray-300 dark:border-gray-600 hover:bg-gray-100 dark:hover:bg-gray-700"
+                title={nextRoute.name}
+              >
+                Next &rarr;
+              </Link>
+            ) : (
+              <span className="px-2 py-1 text-sm rounded border border-gray-200 dark:border-gray-700 text-gray-300 dark:text-gray-600 cursor-not-allowed">
+                Next &rarr;
+              </span>
+            )}
+          </div>
+        </div>
         <button
           onClick={() => setShowCreate(true)}
           className="px-4 py-2 text-sm font-medium rounded-md bg-blue-600 text-white hover:bg-blue-700"