Tests hardcode /Users/dkundel/code/codex-plugin, so npm test fails outside the original machine

[VOIDXAI]

Bug

npm test fails on a fresh clone because the test suite hardcodes one developer-specific checkout path.

Reproduction

1. Clone this repository anywhere other than /Users/dkundel/code/codex-plugin
2. Run:

   npm test

3. Observe failures like:
   • ENOENT: no such file or directory, open '/Users/dkundel/code/codex-plugin/plugins/codex/commands/review.md'
   • MODULE_NOT_FOUND for /Users/dkundel/code/codex-plugin/plugins/codex/scripts/codex-companion.mjs

Root Cause

Both test files set ROOT to an absolute path instead of deriving it from the checked-out repository location:

• tests/commands.test.mjs
• tests/runtime.test.mjs

That makes the suite depend on the original author's local filesystem layout.

Impact

• New contributors cannot run the full test suite successfully on their own machines.
• CI or any clean environment will fail unless it happens to mirror that exact path.
• Real regressions are masked by path-related failures.

Suggested Fix

Resolve the repo root relative to the test files at runtime, for example via import.meta.url, and add a regression check that does not depend on a machine-specific absolute path.