fix: render primitive types from spec config

[juliosuas]

Fixes #97. Moves primitive type definitions into spec-config.yaml and renders them through the spec generator, so Color and Dimension are driven by the same config source as sections, units, typography properties, and component sub-tokens. Validation: focused spec-config/spec-gen tests passed; generate --check passed; full bun run test, bun run lint, bun run build, and git diff --check passed.

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[rajpratham1]

This is a well-structured refactor that moves primitive type definitions into the shared spec configuration instead of duplicating them inside the generated documentation. It improves maintainability, keeps the specification as a single source of truth, and includes appropriate validation and regression tests.