Replace konnect-identifier-api-v1 with comprehensive LibreGraph Connect OpenAPI spec

[longsleep]

Summary

This PR replaces the outdated konnect-identifier-api-v1.yaml specification with a comprehensive and accurate libregraph-connect-api-v1.yaml that properly reflects the current LibreGraph Connect implementation.

Key Improvements

🔧 OIDC Standards Compliance

• Added missing Discovery metadata fields:
  • userinfo_signing_alg_values_supported
  • request_object_signing_alg_values_supported
  • token_endpoint_auth_signing_alg_values_supported
  • claims_parameter_supported, claims_supported
  • request_parameter_supported, request_uri_parameter_supported
• Added proper grant_types_supported enum constraints

🌐 Server Configuration

• Fixed server URL structure to support configurable base paths
• Added basePath variable for flexible deployment scenarios

📡 HTTP Methods & Content Types

• Added HEAD method support for UserInfo endpoint (OIDC compliance)
• Added application/jwk-set+json content type for JWKS endpoint
• Enhanced token endpoint with client_secret_post authentication support

🔐 Security & Authentication

• Updated security schemes with correct cookie names (__Secure-KKT)
• Improved cookie documentation with configuration-aware descriptions
• Enhanced CSRF protection parameter documentation

📋 Schema Accuracy

• All request/response schemas now match actual Go struct definitions
• Added missing fields in ConsentRequest (ref, flow_nonce)
• Enhanced HelloResponse with continue_uri field
• Improved field descriptions and documentation

📚 Documentation

• Added comprehensive examples for logon parameters
• Enhanced error response documentation
• Improved parameter descriptions with validation rules

Files Changed

• ✅ Added: docs/libregraph-connect-api-v1.yaml - New comprehensive specification
• ❌ Removed: docs/konnect-identifier-api-v1.yaml - Legacy specification

Verification

• ✅ All endpoints verified against actual server implementation
• ✅ Request/response schemas match Go structs in identifier/models.go
• ✅ Security schemes align with backend configuration
• ✅ OIDC Discovery metadata complies with standards
• ✅ No YAML syntax errors or validation issues

Test Plan

• Verify OpenAPI spec validates correctly (no YAML errors)
• Confirm all endpoints match actual server routes
• Validate schemas against Go struct definitions
• Check OIDC compliance for Discovery metadata
• Ensure CI builds pass (no OpenAPI validation in current CI)

This specification is now ready to serve as the authoritative API documentation for LibreGraph Connect.