Better Auth OAuth Provider

External OAuth provider plugin package for better_auth.

Upstream ships OAuth provider as @better-auth/oauth-provider, separate from core plugin exports. This gem mirrors that boundary for Ruby.

require "better_auth"
require "better_auth/oauth_provider"

BetterAuth.auth(
  plugins: [
    BetterAuth::Plugins.oauth_provider
  ]
)

OIDC provider remains a core better_auth plugin because upstream still exposes it from better-auth/plugins. OAuth provider is the newer standalone provider package.