Recreate CI/CD workflows for testing branch with spdlog fixes and comprehensive validation

- Recreated testing-ci.yml with multi-compiler testing and dependency management
- Recreated testing-cd.yml with staging deployment and smoke tests
- Recreated testing-validation.yml with API consistency and code quality checks
- Added custom Findspdlog.cmake module with fallback options
- Updated CMakeLists.txt to use custom spdlog module
- Enhanced dependency installation in CI workflows
- Added comprehensive validation jobs for quality assurance

Author: SATOVERSE Developer