Linting: end-to-end test with real oxlint/eslint

[mikn]

Problem

The ts_lint rule exists and passes a test with a fake linter (tests/lint/fake_linter.sh). It has never been tested end-to-end with a real linter binary (oxlint or eslint).

Gazelle auto-detects lint configs (oxlint.json, .eslintrc.*, eslint.config.*) and generates ts_lint targets, but:

1. The generated targets reference @npm//:oxlint_bin or @npm//:eslint_bin which may not exist
2. No example demonstrates real linting
3. The ts_lint rule's interaction with the _validation output group is tested with a stub

Expected behavior

• A test that runs oxlint on real TypeScript code and verifies it catches a lint violation
• A test that verifies the _validation output group fails when lint violations exist
• An example with real lint configuration

Suggested fix

1. Add oxlint to tests/npm/pnpm-lock.yaml
2. Create tests/lint_real/ with an oxlint.json config and a .ts file with a known violation
3. Verify bazel build //tests/lint_real:lint --output_groups=+_validation fails correctly
4. Verify clean code passes

[mikn]

Fixed in PR #14. Real oxlint binary test at tests/lint_real/.