Update CSV data fetching to use API endpoint in Mannschaften components

This commit modifies the loadMannschaften function across multiple components to fetch CSV data from the new API endpoint '/api/mannschaften' instead of the previous static file path '/data/mannschaften.csv'. This change enhances data retrieval consistency and aligns with the updated data management strategy in the application.

components/Navigation.vue

@@ -924,7 +924,7 @@ const toggleMobileSubmenu = (menu) => {
 const loadMannschaften = async () => {
   try {
     const attempt = async () => {
-      const url = `/data/mannschaften.csv?_t=${Date.now()}`
+      const url = `/api/mannschaften?_t=${Date.now()}`
       const response = await fetch(url, { cache: 'no-store' })
       if (!response.ok) return null
       return await response.text()