fix: Remove missing package icon reference from build configuration

- Remove PackageIcon reference from Directory.Build.props
- Icon.png file was not present causing NuGet pack to fail
- This allows successful package creation without icon

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: datlogysoftware

Directory.Build.props

@@ -24,7 +24,6 @@
     <RepositoryUrl>https://github.com/datalogysoft/gis-framework</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
     <PackageTags>gis;geospatial;datalogysoft;datalogy;spatial;mapping;netstandard;dotnet;csharp</PackageTags>
-    <PackageIcon>icon.png</PackageIcon>
     <Description>DatalogySoftware GIS Framework - Powering Next-Generation Geospatial Intelligence for .NET</Description>
 
     <!-- Build Configuration -->