feat(konsistent): validate schemas for declared and exported type definitions

[felixarntz]

Pull Request Description

Adds schema validation to exportTypes and declareTypes, allowing conventions to enforce structural constraints on local TypeScript type aliases and interfaces.

• Supports schema for declared and exported type definitions while keeping it mutually exclusive with from
• Enforces declaration-specific object semantics: configured properties must exist, required properties must be non-optional, and other configured properties must be optional
• Allows partial object validation unless additionalProperties is explicitly false
• Adds unit and end-to-end coverage for valid partial schemas and missing-property failures
• Updates the documentation and generated configuration schemas

Relevant technical choices

Type schemas reuse the existing schema matcher and parsed type-shape representation. Validation intentionally applies only to local definitions and does not resolve re-exports, named references, inheritance, or composed types.

Checklist

• All commits are signed (PRs with unsigned commits cannot be merged)
• Tests have been added / updated
• A changeset has been added (run pnpm changeset in the project root if package files were modified)
• I have reviewed this pull request (self-review)