feat: add pre-registration conformance test

[pcarleton]

Summary

Add conformance test for OAuth pre-registration flow where the server does NOT support Dynamic Client Registration (DCR) and clients must use pre-configured static credentials.

This addresses issue #34 (Client Registration Methods) - specifically the pre-registration section that was previously not covered.

Changes

• Add disableDynamicRegistration option to createAuthServer helper
• Add auth/pre-registration scenario with pre-registered client credentials
• Add MCP_PREREGISTRATION spec reference
• Add context schema for pre-registration credentials
• Add withOAuthRetryWithProvider helper for pre-configured providers
• Add negative test client (auth-test-attempts-dcr.ts) that ignores pre-registered credentials and fails

How it works

The scenario:

1. Configures server with disableDynamicRegistration: true (no registration_endpoint in OAuth metadata)
2. Passes pre-registered client_id and client_secret via context
3. Validates client uses correct credentials at token endpoint via Basic auth
4. Fails if client doesn't make a token request (e.g., tries DCR and fails)

Testing

# Run the pre-registration test
node dist/index.js client \
  --command 'npx tsx examples/clients/typescript/everything-client.ts' \
  --scenario auth/pre-registration

# Run the negative test (should fail)
node dist/index.js client \
  --command 'npx tsx examples/clients/typescript/auth-test-attempts-dcr.ts' \
  --scenario auth/pre-registration

Closes #34

[pkg-pr-new]

Open in StackBlitz

npx https://pkg.pr.new/modelcontextprotocol/conformance/@modelcontextprotocol/conformance@120

commit: a8bbf89