fix: ensure leagueId is retained when editing a team to prevent accidental removal of MyTischtennis link

backend/controllers/myTischtennisUrlController.js

@@ -250,39 +250,37 @@ class MyTischtennisUrlController {
         throw new HttpError('Club team not found', 404);
       }
 
-      let league;
-      
-      // First, try to find existing league by name and season
       const leagueName = completeData.leagueName || completeData.groupname;
-      league = await League.findOne({
-        where: {
-          name: leagueName,
-          seasonId: season.id,
-          clubId: team.clubId
+      let league;
+
+      // The league chosen for a club team is also used by the schedule filters.
+      // Keep that assignment and only enrich it with the MyTischtennis metadata.
+      if (team.leagueId) {
+        league = await League.findOne({
+          where: { id: team.leagueId, clubId: team.clubId }
+        });
+        if (league) {
+          devLog(`Keeping team's existing league: ${league.name} (ID: ${league.id})`);
         }
-      });
+      }
+
+      if (!league) {
+        league = await League.findOne({
+          where: {
+            name: leagueName,
+            seasonId: season.id,
+            clubId: team.clubId
+          }
+        });
+      }
 
       if (league) {
-        devLog(`Found existing league: ${league.name} (ID: ${league.id})`);
-        // Update myTischtennis fields
+        devLog(`Using existing league: ${league.name} (ID: ${league.id})`);
         await league.update({
           myTischtennisGroupId: completeData.groupId,
           association: completeData.association,
           groupname: completeData.groupname
         });
-      } else if (team.leagueId) {
-        // Team has a league assigned, update it
-        league = await League.findByPk(team.leagueId);
-        
-        if (league) {
-          devLog(`Updating team's existing league: ${league.name} (ID: ${league.id})`);
-          await league.update({
-            name: leagueName,
-            myTischtennisGroupId: completeData.groupId,
-            association: completeData.association,
-            groupname: completeData.groupname
-          });
-        }
       } else if (createLeague) {
         // Create new league
         devLog(`Creating new league: ${leagueName}`);

frontend/src/views/TeamManagementView.vue

@@ -1578,12 +1578,16 @@ export default {
           !!String(teamToEdit.value?.plannedLeagueName || '').trim();
         const teamData = {
           name: newTeamName.value.trim(),
-          leagueId: normalizedLeagueId,
           seasonId: selectedSeasonId.value,
           teamGender: newTeamGender.value,
           teamAgeGroup: newTeamAgeGroup.value,
           plannedLeagueName: shouldClearPlannedLeague ? null : (newPlannedLeagueName.value.trim() || null)
         };
+        // Beim Bearbeiten darf ein leeres Auswahlfeld die bestehende Liga- und
+        // damit die MyTischtennis-Verknüpfung nicht versehentlich entfernen.
+        if (!teamToEdit.value || normalizedLeagueId) {
+          teamData.leagueId = normalizedLeagueId;
+        }
         
         if (teamToEdit.value) {
           // Bearbeitung eines bestehenden Teams