fix(generation): fix class jsdoc generation

[avivkeller]

Fixes #37

[Copilot]

Pull request overview

Fixes missing JSDoc emission for generated declare class blocks in the generate-types tool (Issue #37), so class-level documentation is preserved in the resulting types.d.ts.

Changes:

• Extend the internal MergedClassType shape to carry documentation.
• Propagate documentation when converting/merging interface shapes into class shapes.
• Prefix generated class declarations with the captured documentation (matching existing interface behavior).

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