Add YAML pipeline examples for teaching CI/CD

[timothywarner]

Overview

Teaching-ready YAML pipeline examples for AZ-400 course demonstrations.

Files Added

1. Single-Stage CI Pipeline (pipelines/single-stage-ci.yml)

• Basic CI pattern with Node.js
• Testing, linting, coverage
• Clear comments for teaching

2. Multi-Stage CI/CD Pipeline (pipelines/multi-stage-cicd.yml)

• 5 stages: Build → Dev → Staging → Production → Post-Deploy
• Blue-green deployment with slot swapping
• Automated rollback on failure
• Environment approvals

3. GitHub Actions Workflow (.github/workflows/node-azure-deploy.yml)

• GitHub-native CI/CD to Azure
• Environment protection rules
• Security scanning with CodeQL
• Release tagging

4. Documentation (pipelines/README.md)

• Setup instructions
• Teaching points for each pipeline
• Azure resource creation scripts

Benefits

• ✅ Production-ready examples
• ✅ Heavily commented for teaching
• ✅ Covers both Azure Pipelines and GitHub Actions
• ✅ Progressive complexity (single → multi-stage)
• ✅ Real-world patterns (blue-green, rollback, gates)

Perfect for course segments 2 & 3!