feat(WOR-TSK-204): implement configValidate NAPI function

[miguelramos]

• Add config_validate async function to validate workspace configuration
• Add validate_validate_params for parameter validation
• Add parse_validation_error to extract field and message from errors
• Add generate_suggestion for helpful error suggestions
• Add perform_semantic_checks for additional validation warnings
• Re-export config_validate from commands/mod.rs and lib.rs
• Update types/config.rs comments to reflect types are now in use
• Add comprehensive test module with 61 tests for config_validate
• Update packages/workspace-tools/src/index.ts with configValidate export
• Rebuild bindings with build-binding:release and build:node

Story 7.3: Implement configValidate

• Returns validation status (valid: boolean)
• Returns errors array with severity, field, message, suggestion
• Returns warnings array for semantic issues
• Validates config structure via pkg crate validate()
• Adds semantic checks for runtime issues (high parallelism, short timeouts, etc.)