Remove dotnet-ef tool config and IIS publish profiles

Deleted dotnet-tools.json (dotnet-ef config) and IIS publish profiles for .NET 7 and .NET 9 (IISProfileNet7Win64.pubxml, IISProfileNet9Win64.pubxml) to clean up unused deployment and tooling files.

EnvelopeGenerator.API/Models/CustomImages.cs

@@ -0,0 +1,6 @@
+namespace EnvelopeGenerator.GeneratorAPI.Models;
+
+public class CustomImages : Dictionary<string, Image>
+{
+    public new Image this[string key] => TryGetValue(key, out var img) && img is not null ? img : new();
+}