Issue 2: Create Definition entity to replace ModelInput

[adamhjk]

Implement the Definition entity that replaces ModelInput with support for YAML-based storage and CEL expressions.

Key Changes

• Create src/domain/definitions/definition.ts - Definition entity
  • Fields: id, name, tags, attributes, version, inputs (JsonSchema)
  • Support for CEL expressions in attributes: ${{ expression }}
• Create src/domain/definitions/definition_schema.ts - Zod schema
• Create src/infrastructure/persistence/yaml_definition_repository.ts
  • Storage: .swamp/definitions/{type}/{id}.yaml
  • Parse and preserve CEL expressions (don't evaluate on save)
• Create src/infrastructure/persistence/yaml_evaluated_definition_repository.ts
  • Storage: .swamp/definitions-evaluated/{type}/{id}.yaml (gitignored)
  • Stores definitions with CEL expressions evaluated

Integration with Existing CEL System

• Leverage existing src/domain/expressions/expression_evaluation_service.ts
• Update expression context to support:
  • inputs.{param} - Access definition inputs
  • model.{name}.definition.attributes - Reference other model definitions
  • model.{name}.data.{data-name}.attributes - Reference data from other models
  • vault.get(vault_name, key) - Already supported

Acceptance Criteria

• Definition entity supports all design doc fields
• Repository saves/loads definitions as YAML
• CEL expressions preserved in raw definitions
• Evaluated definitions cached in .swamp/definitions-evaluated/
• Integration with existing expression evaluation service
• Unit tests for Definition entity
• Integration test: create definition with CEL expressions, evaluate expressions

Dependencies

None - can be done in parallel with Issue #116

Files to Create

• src/domain/definitions/definition.ts
• src/domain/definitions/definition_schema.ts
• src/domain/definitions/definition_id.ts
• src/infrastructure/persistence/yaml_definition_repository.ts
• src/infrastructure/persistence/yaml_evaluated_definition_repository.ts
• src/domain/definitions/definition_test.ts

Files to Update

• src/domain/expressions/expression_evaluation_service.ts - Add definition context support