Add Generate Spec to CLI & extend toSpec()

[AbhinRustagi]

Summary

Add generate-spec CLI command to export serialized library specifications as JSON, including component signatures, groups, and JSON schema definitions. This enables downstream tooling to consume library metadata for code generation and validation.

Changes

• New CLI Command: openui generate-spec generates a serialized LibrarySpec containing:

  • Component signatures and metadata
  • Component groupings
  • Full JSON schema of all components with descriptions preserved

• API Enhancements:

  • Add toJSONSchema() method to Library class to export component definitions as JSON Schema
  • Add LibrarySpec type that extends BaseSpec with embedded schema
  • Update toSpec() to include the schema alongside signatures and groups
  • Preserve component descriptions in serialized JSON schemas

• Exports: Make LibrarySpec and buildComponentSignature publicly exported from lang-core

• Documentation: Add CLI reference documentation for the new generate-spec command

Testing

• Unit tests verify that toSpec() carries library JSON schema alongside component signatures
• Tests confirm component descriptions are preserved in serialized output