feat(phase-4a): complete Phase 3 implementation and gap analysis

Merges Phase 4a work including:

Implementation:
- Metadata discovery endpoint (/api/.well-known/oauth-authorization-server)
- h-app microformat parser service
- Enhanced authorization endpoint with client info display
- Configuration management system
- Dependency injection framework

Documentation:
- Comprehensive gap analysis for v1.0.0 compliance
- Phase 4a clarifications on development approach
- Phase 4-5 critical components breakdown

Testing:
- Unit tests for h-app parser (308 lines, comprehensive coverage)
- Unit tests for metadata endpoint (134 lines)
- Unit tests for configuration system (18 lines)
- Integration test updates

All tests passing with high coverage. Ready for Phase 4b security hardening.

tests/unit/test_token_endpoint.py

@@ -17,6 +17,7 @@ def test_config(monkeypatch):
     """Configure test environment."""
     # Set required environment variables
     monkeypatch.setenv("GONDULF_SECRET_KEY", "test_secret_key_" + "x" * 32)
+    monkeypatch.setenv("GONDULF_BASE_URL", "https://auth.example.com")
     monkeypatch.setenv("GONDULF_DATABASE_URL", "sqlite:///:memory:")
 
     # Import after environment is set