Add Kleinunternehmerregelung to settings page

Server/Components/Pages/SettingsPage.razor

@@ -81,6 +81,19 @@
       <InputText DisplayName="Steuernummer" class="form-control"
                  @bind-Value="@SettingsData.Instance.SellerAddress.TaxId"></InputText>
     </div>
+    
+    <div class="mb-3">
+      <div style="display: inline;">
+        <div class="btn-group btn-group-sm" role="group">
+          <input type="radio" class="btn-check" name="options-outlined" id="switch-on" autocomplete="off" checked="@(SettingsData.Instance.Kleinunternehmer)" @onchange="@(() => SettingsData.Instance.Kleinunternehmer = true)">
+          <label class="btn btn-outline-primary" for="switch-on">An</label>
+
+          <input type="radio" class="btn-check" name="options-outlined" id="switch-off" autocomplete="off" checked="@(!SettingsData.Instance.Kleinunternehmer)" @onchange="@(() => SettingsData.Instance.Kleinunternehmer = false)">
+          <label class="btn btn-outline-primary" for="switch-off">Aus</label>
+        </div>
+      </div>
+      Kleinunternehmerregelung
+    </div>
   </div>
   <div class="col-md-6 col-xl-4 col-xxl-3">
     <hr/>

Server/Data/SettingsData.cs

@@ -14,6 +14,8 @@ namespace Server.Data
 
         public PaymentData PaymentData { get; set; } = new();
         
+        public bool Kleinunternehmer { get; set; }
+        
         public string? Comment { get; set; }
         
         public string? Logo { get; set; }