feat: refactor doctor to use SDK error detection instead of manual validation (fixes #26) (#27)

- Add SdkErrorDetector class to capture and translate MCP SDK errors into doctor test results
- Create SDK-based JSON-RPC compliance tests that leverage SDK error handling
- Replace manual validation in base-protocol tests with SDK error detection
- Add comprehensive test coverage for new SDK error detection system
- Add performance_issue type to ISSUE_TYPE enum for timeout error classification
- Add connection feature to ProtocolFeature type for lifecycle tests
- Enable SDK error detection by default in DoctorConfig experimental options

This eliminates duplicate validation logic by leveraging the SDK's built-in error
detection and provides the same comprehensive spec compliance testing through
SDK error translation rather than manual validation.

Author: steviec

.claude

@@ -0,0 +1 @@
+../../../claude-setups/claude-2/