Refactor admin panel into categorized navigation

frontend/src/components/AppShell.vue

@@ -25,7 +25,7 @@ const navItems = [
 ]
 
 const currentLabel = computed(
-  () => navItems.find((item) => item.to === route.path)?.label ?? 'Awards',
+  () => navItems.find((item) => route.path === item.to || route.path.startsWith(`${item.to}/`))?.label ?? 'Awards',
 )
 
 const visibleNavItems = computed(() =>
@@ -103,7 +103,7 @@ async function login(role: 'viewer' | 'admin') {
               :key="item.to"
               :to="item.to"
               class="rounded-full px-4 py-2 transition hover:bg-violet-50 hover:text-violet-700"
-              :class="route.path === item.to ? 'bg-violet-100 text-violet-800' : ''"
+              :class="route.path === item.to || route.path.startsWith(`${item.to}/`) ? 'bg-violet-100 text-violet-800' : ''"
             >
               {{ item.label }}
             </RouterLink>

frontend/src/components/admin/AdminSeasonToolbar.vue

@@ -0,0 +1,44 @@
+<script setup lang="ts">
+import { computed } from 'vue'
+import Select from 'primevue/select'
+
+import { useAwardsStore } from '../../stores/awards'
+
+const store = useAwardsStore()
+
+const seasons = computed(() => store.adminSeasons)
+const selectedSeasonId = computed({
+  get: () => store.adminSelectedSeasonId,
+  set: async (value) => {
+    if (!value) return
+    await store.loadAdminSeasonDetail(value)
+  },
+})
+
+const seasonOptions = computed(() =>
+  seasons.value.map((season) => ({
+    label: `${season.year} · ${season.name}`,
+    value: season.id,
+  })),
+)
+</script>
+
+<template>
+  <div class="flex flex-col gap-4 rounded-[26px] border border-violet-100 bg-white/80 px-5 py-5 md:flex-row md:items-center md:justify-between">
+    <div>
+      <p class="text-xs font-semibold uppercase tracking-[0.28em] text-violet-500">Arbeitskontext</p>
+      <p class="mt-2 text-sm text-slate-500">Die gewaehlte Season steuert Kategorien, Kandidaten und Review-Queues im gesamten Admin-Bereich.</p>
+    </div>
+
+    <div class="grid gap-3 md:min-w-[330px]">
+      <label class="text-sm font-semibold text-slate-600">Season</label>
+      <Select
+        v-model="selectedSeasonId"
+        :options="seasonOptions"
+        option-label="label"
+        option-value="value"
+        class="w-full"
+      />
+    </div>
+  </div>
+</template>