feat(mannschaften): align public pages with season query logic

pages/mannschaften/[slug].vue

@@ -325,7 +325,7 @@
         <!-- Zurück-Button -->
         <div class="text-center">
           <NuxtLink
-            to="/mannschaften"
+            :to="{ path: '/mannschaften', query: selectedSeason ? { season: selectedSeason } : {} }"
             class="inline-flex items-center px-6 py-3 bg-primary-600 hover:bg-primary-700 text-white font-semibold rounded-lg transition-colors"
           >
             ← Zurück zur Übersicht
@@ -359,6 +359,19 @@ import { ref, computed, onMounted } from 'vue'
 import { Users } from 'lucide-vue-next'
 
 const route = useRoute()
+
+const getCurrentSeasonSlug = () => {
+  const now = new Date()
+  const year = now.getFullYear()
+  const startYear = now.getMonth() >= 6 ? year : year - 1
+  const endYear = startYear + 1
+  return `${String(startYear).slice(-2)}--${String(endYear).slice(-2)}`
+}
+
+const selectedSeason = computed(() => {
+  const value = String(route.query.season || '').trim()
+  return /^\d{2}--\d{2}$/.test(value) ? value : getCurrentSeasonSlug()
+})
 const mannschaft = ref(null)
 const mannschaftSpielplan = ref([])
 const spielplanSeason = ref('')
@@ -413,7 +426,9 @@ async function fetchCsvText(url) {
 
 const loadMannschaften = async () => {
   try {
-    const csv = await fetchCsvText('/api/mannschaften')
+    const params = new URLSearchParams()
+    if (selectedSeason.value) params.set('season', selectedSeason.value)
+    const csv = await fetchCsvText(`/api/mannschaften${params.toString() ? `?${params.toString()}` : ''}`)
     if (!csv) return
     const lines = csv.split('\n').filter(line => line.trim() !== '')
     
@@ -485,7 +500,9 @@ const loadTeamTable = async () => {
 
   try {
     const params = new URLSearchParams({ team: mannschaft.value.mannschaft })
-    if (spielplanSeason.value) {
+    if (selectedSeason.value) {
+      params.set('season', selectedSeason.value)
+    } else if (spielplanSeason.value) {
       params.set('season', spielplanSeason.value)
     }
 
@@ -594,7 +611,9 @@ const loadSpielplan = async () => {
   spielplanError.value = ''
 
   try {
-    const response = await fetch('/api/spielplan')
+    const params = new URLSearchParams()
+    if (selectedSeason.value) params.set('season', selectedSeason.value)
+    const response = await fetch(`/api/spielplan${params.toString() ? `?${params.toString()}` : ''}`)
     const result = await response.json()
 
     if (!result.success) {