test[notask]: protect SDK 0.18 schema package contract

[localhost41]

Summary

• add a consumer-facing contract test for the @qvac/sdk/schemas 0.18 package entrypoint
• verify the runtime/declaration export targets and the three documented public aliases
• verify every llama.cpp config field description matches the committed contract/schema.json

Verification

• tsx test/schemas-package-contract.test.ts
• npm run contract:check
• npm pack inspection confirms dist/src/schemas/public.js and public.d.ts ship in the tarball

The repository CI build should run the test after the normal SDK build. The local full build was limited by stale preinstalled native dependency versions; the focused package contract and committed contract checks pass.

[github-actions]

Review Status

Current Status: ❌ PENDING
Approvals so far: none

Pending reviews: Needs 1 Management or Team Lead, and 1 more from Management, Team Lead, or Member.