Consolidate GitHub workflows and update to .NET 8.0

Changes:
- Removed redundant tests.yml workflow
- Updated ci-cd.yml to use .NET 8.0.x (from 6.0.x)
- Single comprehensive CI/CD pipeline now handles all testing, coverage, and analysis

The ci-cd.yml workflow provides:
- Build and test execution
- Code coverage collection and reporting
- Coverage badges and PR comments
- Code quality analysis with dotnet format
- Efficient NuGet package caching

This eliminates duplicate test runs and reduces GitHub Actions minutes usage.

Author: TechieGuy12

.github/workflows/ci-cd.yml

@@ -7,7 +7,7 @@ on:
     branches: [ main, develop, developv2 ]
 
 env:
-  DOTNET_VERSION: '6.0.x'
+  DOTNET_VERSION: '8.0.x'
 
 jobs:
   build-and-test: