[#79] Entities: Remove EF proxies

Elwig/Windows/AdministrationWindow.cs

@@ -349,7 +349,6 @@ namespace Elwig.Windows {
                 using var ctx = new AppDbContext();
                 list = await ctx.PlzDestinations
                    .Where(p => p.Plz == plz)
-                   .Include(p => p.Ort)
                    .ToListAsync();
             }