feat: implement workflow yaml validation and schema

[alexeyv]

Implement Workflow YAML Validation and Schema

This PR introduces comprehensive validation for all [workflow.yaml] files using Zod schema validation, ensuring consistency and catching configuration errors early in development.

🎯 Overview

Implements a robust validation system for workflow YAML files with:

• Zod-based schema validation with comprehensive field coverage
• Variable reference validation to catch typos in placeholders, config vars, and template vars
• Non-fatal warning system for unknown fields (allows workflow-specific customization)
• Comprehensive test suite with 13 test fixtures
• CLI validator for CI/CD integration

📦 What's Included

New Files

• tools/schema/workflow.js (450 lines) - Core Zod schema with variable reference validation
• tools/validate-workflow-schema.js (166 lines) - CLI validator for all workflow files
• test/test-workflow-schema.js (302 lines) - Comprehensive test runner
• test/fixtures/workflow-schema/ - 13 test fixtures (11 invalid, 2 valid scenarios)

Key Features

1. Schema Validation

   • Required fields: name, description, instructions
   • Kebab-case enforcement for workflow names
   • Support for all optional fields with proper typing
   • Flexible .catchall() for workflow-specific variables

2. Variable Reference Validation

   • Path placeholders: {placeholder} - validates against 60+ known placeholders
   • Config variables: {config_source}:variable - validates against known config vars
   • Template variables: {{variable}} - validates against known template vars
   • Detects malformed syntax (unclosed braces, missing colons)

3. Warning System

   • Non-fatal warnings for unknown fields
   • Aggregated reporting in CLI validator
   • Allows workflow-specific customization without breaking validation

4. Testing & CI Integration

   • Integrated into npm test and npm run validate:schemas
   • Metadata-driven test expectations in YAML comments
   • Categorized test reporting with pass/fail statistics

🧹 Cleanup

Removed legacy author field from 65 workflow files across all modules (identified as LLM hallucination/legacy field not used by the system).

📊 Changes Summary

• 85 files changed: +1,106 insertions, -92 deletions
• Scripts updated: Added workflow validation to test:schemas and validate:schemas
• Test coverage: 13 fixtures covering validation scenarios

✅ Testing

All validation tests pass:

npm run test:schemas        # Run test suite
npm run validate:schemas    # Validate all workflow files

[alexeyv]

This will have to be reworked to fit the new workflow format.