Better Auth OAuth 2.1 Provider

[chriswritescode-dev]

OAuth 2.1 Provider plugin enabling auth server as OAuth provider with OIDC compatibility, dynamic client registration, and JWT signing.

Context

This is part of the Authentication roadmap using BetterAuth.

Scope

• OAuth 2.1 Provider plugin integration
• OIDC compatibility layer
• Dynamic client registration
• JWT signing and validation

Related

• Passkey / Yubikey Support (separate issue)
• See ROADMAP.md for full auth phase details