- Convert remaining node:test → vitest imports in packages/* and studio/*
- Fix mock.callCount() → mock.callCount property access for vitest compat
- Fix mock.calls[N].arguments → mock.calls[N] for vitest compat
- Update tsconfig.extensions.json to exclude test files from tsc
- Harden migrate-to-vitest-all.mjs regex for single quotes and optional semicolons