Refactor NuGet package handling across multiple CI runners and documentation. Update paths to use .nuget/packages instead of local-nugets. Enhance README files for clarity on usage and environment setup. Add script to automate the addition of test projects to the solution.

devops/scripts/add-test-projects.ps1

@@ -0,0 +1,45 @@
+# add-test-projects.ps1 - Add all test projects to StellaOps.Tests.sln
+# Sprint: SPRINT_20251226_007_CICD
+
+$ErrorActionPreference = 'Continue'
+
+$slnPath = "src\StellaOps.Tests.sln"
+$srcPath = "src"
+
+Write-Host "=== Adding test projects to StellaOps.Tests.sln ==="
+Write-Host "Solution: $slnPath"
+
+# Find all test project files
+$testProjects = Get-ChildItem -Path $srcPath -Recurse -Filter "*Tests.csproj" |
+    Where-Object {
+        $_.Name -notlike "*Testing.csproj" -and
+        $_.Name -notlike "*TestKit.csproj" -and
+        $_.FullName -notlike "*node_modules*" -and
+        $_.FullName -notlike "*bin*" -and
+        $_.FullName -notlike "*obj*"
+    }
+
+Write-Host "Found $($testProjects.Count) test projects"
+
+$added = 0
+$failed = 0
+
+foreach ($proj in $testProjects) {
+    $relativePath = $proj.FullName.Replace((Get-Location).Path + "\", "")
+    Write-Host "Adding: $relativePath"
+
+    $result = dotnet sln $slnPath add $proj.FullName 2>&1
+
+    if ($LASTEXITCODE -eq 0) {
+        $added++
+    } else {
+        Write-Host "  Failed: $result" -ForegroundColor Yellow
+        $failed++
+    }
+}
+
+Write-Host ""
+Write-Host "=== Summary ==="
+Write-Host "Added: $added"
+Write-Host "Failed: $failed"
+Write-Host "Total: $($testProjects.Count)"