Generated template: lint does not cover test files, causing unnoticed Prettier violations in tests

In a freshly generated project from `project-seed`, linting is scoped to `app/` only.
As a result, files in `test/` are not checked by ESLint (including `eslint-plugin-prettier`).

Observed behavior:

- `pnpm lint` passes
- A test file can still have a Prettier violation (example: missing final newline) without lint failing

Expected behavior:

- `pnpm lint` should also validate files in `test/` and config files
- Prettier violations across the project should be reported by lint