Azure DevOps React CI/CD Setup

I have a React-based web application and I need a clean, repeatable CI/CD pipeline running inside Azure DevOps. The goal is for each push to the main branch to trigger an automated build, run unit tests, and deploy the compiled artefact to the Azure environment I’ll point you to once we start.

Current context
• Project type: Web application
• Stack: React (with the usual npm/yarn workflow)
• Build & release orchestration: Azure DevOps Pipelines, using its hosted agents and tasks

What I expect
1. YAML-driven pipeline stored in the repo
2. Separate stages for build, test, and deploy, with clear naming and logs
3. Environment variables and secrets handled through Azure DevOps Library and variable groups
4. Simple rollback strategy (for example, keep the previous successful release on standby)
5. A short README explaining how to trigger manual runs, promote between stages, and extend the pipeline later

Acceptance criteria
• A commit to main automatically produces a production deployment without manual steps
• Pipeline passes on a fresh checkout with no local configuration tweaks
• All steps are visible in Azure DevOps with green checks, including at least one unit-test task
• Documentation lives in the repo and matches the actual pipeline implementation

If anything in the stack needs clarification, let me know early so we can lock it down and move swiftly.