feat(TER-345): implement core validation API bindings for Node.js

[ericpsimon]

Summary

Implements NAPI bindings for the core validation API, exposing ValidationSuite, Check, and related types to TypeScript.

Implementation Details

Core Modules Added:

• src/types.rs: Type conversions and enums (Level, ConstraintStatus, ValidationResult, etc.)
• src/check.rs: Check and CheckBuilder with various constraint methods
• src/validation_suite.rs: ValidationSuite and builder with async run capability
• src/data_source.rs: DataSource abstraction supporting CSV, Parquet, and JSON
• src/lib.rs: Main NAPI module setup and exports

Key Features:

✅ ValidationSuite can be created from TypeScript
✅ Check builder pattern works in TypeScript
✅ Async run() method properly returns Promise
✅ Error handling converts Rust errors to JS exceptions
✅ TypeScript definitions are correctly generated
✅ Basic validation suite can be built and executed

TypeScript API:

// Create data source
const data = await DataSource.fromCsv('data.csv');

// Build checks
const check = new CheckBuilder('completeness')
  .level(Level.Error)
  .isComplete('column', 0.95);

// Create validation suite
const suite = ValidationSuite.builder('my_suite')
  .addCheck(check)
  .build();

// Run validation
const result = await suite.run(data);

Test Coverage

• Basic module functions
• Level enum exports
• CheckBuilder configuration and creation
• ValidationSuite builder pattern
• DataSource creation from CSV/Parquet/JSON
• Full end-to-end validation workflow
• Error handling

Linear Ticket

Implements: TER-345

🤖 Generated with Claude Code

[ericpsimon]

Closing as duplicate. This PR is now properly stacked as #55 which targets the 10-03 branch.