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

- Replace outdated konnect-identifier-api-v1.yaml with libregraph-connect-api-v1.yaml
- Add missing OIDC Discovery metadata fields for standards compliance:
  - userinfo_signing_alg_values_supported
  - request_object_signing_alg_values_supported
  - claims_parameter_supported, claims_supported
  - request_parameter_supported, request_uri_parameter_supported
- Fix server URL configuration to support configurable base paths
- Add missing HTTP methods (HEAD for UserInfo endpoint)
- Add missing content types (application/jwk-set+json for JWKS)
- Update security schemes with correct cookie names (__Secure-KKT)
- Enhance request/response schemas to match actual Go implementation
- Add client_secret_post authentication method support for token endpoint
- Improve documentation with proper field descriptions and examples

This comprehensive specification accurately reflects the current LibreGraph Connect
implementation and ensures OIDC standard compliance.

Author: longsleep