bug(markdown): MarkdownVisitor omits map and scalar declarations and mislabels declaration types #321

Expected Behavior

When generating Markdown documentation using MarkdownVisitor:

1. Map Declarations should be rendered with their name, key type, value type, and any description decorators.
2. Scalar Declarations should be rendered with their name, underlying primitive type, default value, validation constraints (e.g., regex, length bounds, range bounds), and description decorators.
3. Declaration Stereotypes in section headings should accurately reflect the declaration kind: (Asset), (Participant), (Transaction), (Event), and (Concept).
4. Table column headers should be spelled correctly (Constraints instead of Contraints).

Actual Behavior

1. Maps and scalars are completely omitted: In lib/codegen/fromcto/markdown/markdownvisitor.js, visitModelFile writes ## Overview reporting map and scalar counts (- 6 maps, - 2 scalars), but the visitor never implements visitMapDeclaration or visitScalarDeclaration. The fallback no-op methods from BaseVisitor run, resulting in zero documentation generated for maps or scalars.
2. All non-enum classes are labeled (Concept): visitClassDeclaration hardcodes ### ${classDeclaration.getName()} (Concept). Because visitAssetDeclaration, visitParticipantDeclaration, visitTransactionDeclaration, and visitEventDeclaration are not overridden, all assets, participants, transactions, and events are documented as concepts (e.g., ### Equipment (Concept) instead of ### Equipment (Asset)).
3. Column header typo: Line 143 writes | Contraints | instead of | Constraints |.
4. No dedicated unit tests: test/codegen/fromcto/markdown/ currently does not exist.

Steps to Reproduce

1. Load a model file containing maps, scalars, assets, transactions, and events (such as test/codegen/fromcto/data/model/hr_base.cto + hr.cto).
2. Run MarkdownVisitor on the ModelManager.
3. Inspect models.md:
   • ## Overview reports counts for maps and scalars, but neither appears in the document.
   • Assets and participants (like Equipment and Person) appear under ### Equipment (Concept) and ### Person (Concept).
   • The field table has the header | Contraints |.

Context

• Target: markdown
• File: lib/codegen/fromcto/markdown/markdownvisitor.js

Pull Request

A fix with comprehensive unit tests and snapshot updates is ready to be submitted.