test: prototype component-aware base ui selectors

[tmm]

Type-only prototype of component-aware selector completion using a Zyzz-owned catalog and real Base UI 1.8 types. No runtime API or compiler changes.

// The existing component import supplies selector context.
style(Select.Item, {
  selectors: {
    "&[data-highlighted]": { backgroundColor: "blue" },
  },
})

The TypeScript language-service test verifies Item, Popup, Trigger, side values, nested selector blocks, and unsupported-component behavior. It also demonstrates the structural collision: an unrelated component with the same callback-state shape receives the same hints. Arbitrary CSS selectors remain allowed.

Upstream cooperation could attach an optional type-only attribute schema to each Base UI component export, including attribute value unions. Zyzz could consume that schema instead of matching state shapes, without changing the authoring syntax or adding runtime metadata. The fixture README includes an illustrative declaration and production follow-up requirements.

Validation: completion/consumer checks pass on TypeScript 6, focused TypeScript 7 checking passes, both styleFunction type-bench fixtures pass, and scoped formatting/lint pass. Repository-wide pnpm check:types was killed with exit 137 in this orb and is not reported as passing. No browser behavior is claimed by this type-only experiment.