Auth Implementation Comprehensive guide for implementing authentication and authorization in web applications. Covers session-based auth, JWT, OAuth 2.0, SSO, API keys, RBAC/ABAC, and security hardening across all major frameworks and libraries. Decision Matrix Use this table to pick the right approach and library for your stack: | Use Case | Framework | Recommended Approach | Library | Reference | |----------|-----------|---------------------|---------|-----------| | Full-stack app, social login | Next.js App Router | OAuth + sessions | Auth.js v5 | NEXTAUTH-AUTHJS.md | | Full-stack app, ema…