Slate v2 Core Package Test Script Closure

Goal

Make the core package proof lanes runnable package-by-package instead of only through root-level custom commands.

Completed

• added a package-local test script to:
  • packages/slate/package.json
  • packages/slate-history/package.json
• fixed the slate-hyperscript package-local test script so it runs from the repo root where the shared mocha dependency actually exists under Yarn PnP
• widened the root test:mocha lane so it includes the full slate-hyperscript fixture suite, not just the smoke file

Verification

• yarn workspace slate run test
• yarn workspace slate-history run test
• yarn workspace slate-hyperscript run test
• yarn test:mocha