fix change default club:

Der Fix teilt die Operation in zwei Schritte:
  1. Alle IsDefault auf false → SaveChanges
  2. Neuen Default auf true → SaveChanges

  Das verhindert, dass EF Core temporär zwei IsDefault = true Einträge hat, was den Filtered Unique Index verletzen würde.

src/Koogle.Application/Services/UserService.cs

@@ -316,13 +316,18 @@ public class UserService : IUserService
         // Update default club if specified
         if (dto.DefaultClubId.HasValue)
         {
-            var memberships = await _appDb.UserProfileClubs
-                .Where(upc => upc.UserProfileId == profile.Id)
-                .ToListAsync(ct);
-
-            foreach (var m in memberships)
+            // First: clear all defaults (to avoid unique index violation)
+            foreach (var m in profile.Clubs)
             {
-                m.IsDefault = m.ClubId == dto.DefaultClubId.Value;
+                m.IsDefault = false;
+            }
+            await _appDb.SaveChangesAsync(ct);
+
+            // Then: set the new default
+            var newDefault = profile.Clubs.FirstOrDefault(m => m.ClubId == dto.DefaultClubId.Value);
+            if (newDefault != null)
+            {
+                newDefault.IsDefault = true;
             }
         }
 

src/Koogle.Web/Components/Pages/Days/Days.razor

@@ -50,10 +50,13 @@
             Filtern
         </MudButton>
         <MudSpacer />
-        <MudButton Variant="Variant.Filled" Color="Color.Primary" StartIcon="@Icons.Material.Filled.Add"
-                   OnClick="OpenCreateDialog">
-            Neuer Spieltag
-        </MudButton>
+        @if (AuthState.Value.IsClubEditor || AuthState.Value.IsClubTreasurer || AuthState.Value.IsClubAdmin || AuthState.Value.IsSuperAdmin)
+        {
+            <MudButton Variant="Variant.Filled" Color="Color.Primary" StartIcon="@Icons.Material.Filled.Add"
+                       OnClick="OpenCreateDialog">
+                Neuer Spieltag
+            </MudButton>
+        }
     </ToolBarContent>
     <HeaderContent>
         <MudTh><MudTableSortLabel SortBy="new Func<DaySummaryDto, object>(x => x.PostDate)">Datum</MudTableSortLabel></MudTh>