- typecheck now also runs tsc over tsconfig.test.json (test files were
never type-checked before).
- Delete tests/unit/background.test.ts, which only asserted the vitest
chrome mock's own behavior — every remaining test imports production
code from src/lib.
- Baseline mock gains runtime.id, storage.session/remove, contextMenus,
and tabs.sendMessage.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
