fix(kyberforge): apply audit findings across skill factory trio

- skill-audit: promote internal-working gotcha to ## Gotchas section;
  narrow cross-plugin path check to exclude tests/ (dev-only, repo-level
  deps are expected); require tests/README.md to declare that dependency
- skill-write/skill-improve: reorder descriptions to lead with "Use when..."
  for consistency with skill-audit and the agentskills.io spec trigger pattern
- skill-write: add tests/README.md with self-contained bats setup instructions;
  remove cross-skill reference to skill-audit's tests/README.md

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

plugins/kyberforge/skills/skill-write/tests/README.md

@@ -0,0 +1,28 @@
+# tests/
+
+Test files for scripts bundled with this skill.
+
+## Dependencies
+
+Tests require [bats-support](https://github.com/bats-core/bats-support) and
+[bats-assert](https://github.com/bats-core/bats-assert). The test files load
+helpers from the repo root's `tests/test_helper/`.
+
+From the repo root:
+
+```bash
+git clone https://github.com/bats-core/bats-support tests/test_helper/bats-support
+git clone https://github.com/bats-core/bats-assert tests/test_helper/bats-assert
+```
+
+Run all tests for this skill (from the repo root):
+
+```bash
+bats plugins/kyberforge/skills/skill-write/tests/
+```
+
+## Files
+
+| File | Purpose |
+|------|---------|
+| `new-skill.bats` | Bats test suite for `scripts/new-skill.sh` |