chore(test): normalize test setup — fix build, remove dead config

- Add @types/express to devDependencies (was only a peerDep, broke build)
- Remove unnecessary vite devDep (vitest bundles it)
- Align vitest.config.ts to standard template
- Delete dead jest.config.js
- Build and all 8 tests pass

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: vveerrgg