6 test files across 4 packages (auth-ui, dashboard-components,
dashboard-shell, react-auth) failed with 'document is not defined'
when run from the monorepo root because the root vitest config uses
environment: 'node'. The package-local configs set happy-dom but are
ignored when vitest is invoked from root.
Fix: Add per-file '// @vitest-environment happy-dom' annotations,
which is the recommended vitest pattern for mixed-environment monorepos.
This ensures tests work regardless of which config is loaded.
Recovers 148 tests across 6 files.