feat: Complete Issue #8 - Detailed Validation Error Reporting and CLI Enhancements

Major Features:
- Implement comprehensive validation error reporting system (Issue #8)
- Add direct CLI access with 'markitect' command
- Create extensive makefile targets for CLI usage
- Enhance schema validation with detailed error collection

Components Added:
- markitect/validation_error.py: ValidationError system with 8 error types
- Enhanced markitect/schema_validator.py: Detailed error reporting methods
- markitect/cli.py: Enhanced with --detailed-errors and --error-format options
- visualize_schema.py: Schema visualization with ASCII and colorful modes
- Comprehensive test suite for validation error reporting

CLI Enhancements:
- Direct 'markitect' command access for all operations
- Makefile targets for typical CLI usage (cli-help, cli-ingest, etc.)
- Support for text, JSON, and markdown error output formats
- Backward compatibility with existing validation functionality

Testing:
- 11 comprehensive tests for Issue #8 validation error reporting
- Tests for schema validation, visualization, and CLI integration
- 100% test coverage for validation error scenarios

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

markitect/exceptions.py

@@ -146,4 +146,26 @@ class InvalidDepthError(MarkitectError):
     - Depth values exceed reasonable limits
     - Depth configuration is invalid
     """
+    pass
+
+
+class SchemaValidationError(MarkitectError):
+    """Errors during schema validation process.
+
+    Raised when:
+    - Schema validation process fails
+    - Document structure analysis fails
+    - Validation comparison encounters errors
+    """
+    pass
+
+
+class InvalidSchemaError(MarkitectError):
+    """Errors related to invalid JSON schemas.
+
+    Raised when:
+    - JSON schema format is invalid
+    - Schema doesn't conform to JSON Schema specification
+    - Schema file cannot be loaded or parsed
+    """
     pass