Add Azure Pipelines and GitLab CI documentation

Complete Phase 1.1 of documentation expansion plan by adding comprehensive
CI/CD integration guides for Azure Pipelines and GitLab CI/CD.

New documentation includes:
- Azure Pipelines: Complete guide with multi-stage pipelines, variable groups,
  Azure Key Vault integration, and Azure Artifacts publishing
- GitLab CI/CD: Complete guide with Docker executors, CI/CD variables,
  GitLab Package Registry, and multi-stage pipelines

Both guides include:
- Quick start examples
- Installation options with caching strategies
- Cross-platform build configurations
- Secret management best practices
- Artifact publishing workflows
- Complete psakefile.ps1 examples
- Troubleshooting sections
- Advanced patterns

Updated sidebars.ts to include new CI/CD examples in the "CI Examples" category,
positioned before legacy CI platforms.

Author: claude