Update GitHub Actions to .NET 10, add workflow and docs to solution

.NET version upgrade and solution maintenance

  -- Updated GitHub Actions workflow to use .NET 10.0.x instead of 9.0.x.
  -- Changed VisualStudioVersion in SmartSelector.sln to 18.0.11018.127.
  -- Added .github/copilot-instructions.md and .github/workflows/smart-select.yml as solution items for better documentation and CI visibility.

Author: eglauko

.github/workflows/smart-select.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: '9.0.x'
+          dotnet-version: '10.0.x'
 
       - name: Build and pack SmartSearch Abstractions
         run: dotnet build ./src/RoyalCode.SmartSelector/RoyalCode.SmartSelector.csproj -c Release -o ./publish/RoyalCode.SmartSelector

src/SmartSelector.sln

@@ -7,10 +7,12 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "RoyalCode.SmartSelector", "
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".items", ".items", "{8EC462FD-D22E-90A8-E5CE-7E832BA40C5D}"
 	ProjectSection(SolutionItems) = preProject
+		.github\copilot-instructions.md = .github\copilot-instructions.md
 		Directory.Build.props = Directory.Build.props
 		docs.md = docs.md
 		libs.targets = libs.targets
 		..\README.md = ..\README.md
+		..\.github\workflows\smart-select.yml = ..\.github\workflows\smart-select.yml
 		tests.targets = tests.targets
 	EndProjectSection
 EndProject