Refactor Api-Client

Add Exceptionhandler, AlertService JSON-Converter
AppSettings via DI

Reformat Code

Jugenddienst Stunden/App.xaml

@@ -1,4 +1,5 @@
-<?xml version = "1.0" encoding = "UTF-8" ?>
+<?xml version="1.0" encoding="UTF-8"?>
+
 <Application xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
              xmlns:local="clr-namespace:Jugenddienst_Stunden"
@@ -11,4 +12,4 @@
             </ResourceDictionary.MergedDictionaries>
         </ResourceDictionary>
     </Application.Resources>
-</Application>
+</Application>