chore: Upgrade to .NET 10

This PR upgrades the project to .NET 10 (latest stable release).

Changes:
- Updated all .csproj files to target net10.0
- Updated global.json to SDK 10.0.100 with latestFeature rollForward
- Updated GitHub Actions workflows to use .NET 10.x and setup-dotnet@v5
- Verified successful build locally

Migration notes:
- .NET 10 includes C# 13 language features
- All NuGet packages should be compatible
- CI/CD will validate cross-platform builds

Author: phmatray

global.json

@@ -1,7 +1,6 @@
 {
   "sdk": {
-    "version": "10.0.0",
-    "rollForward": "latestMajor",
-    "allowPrerelease": false
+    "version": "10.0.100",
+    "rollForward": "latestFeature"
   }
-}
+}