fix: address critical code review issues for validation improvements

- Fix type safety vulnerability in enhanced-config-validator.ts
  - Added proper type checking before string operations
  - Return early when nodeType is invalid instead of using empty string

- Improve error handling robustness in MCP server
  - Wrapped validation in try-catch to handle unexpected errors
  - Properly re-throw ValidationError instances
  - Add user-friendly error messages for internal errors

- Write comprehensive CHANGELOG entry for v2.10.3
  - Document fixes for issues #58, #68, #70, #73
  - Detail new validation system features
  - List all enhancements and test coverage

Addressed HIGH priority issues from code review:
- Type safety holes in config validator
- Missing error handling for validation system failures
- Consistent error types across validation tools

CLAUDE.md

@@ -180,6 +180,9 @@ The MCP server exposes tools in several categories:
 - Sub-agents are not allowed to spawn further sub-agents
 - When you use sub-agents, do not allow them to commit and push. That should be done by you
 
+### Development Best Practices
+- Run typecheck and lint after every code change
+
 # important-instruction-reminders
 Do what has been asked; nothing more, nothing less.
 NEVER create files unless they're absolutely necessary for achieving your goal.