Remove deprecated skill improvement and packaging scripts

- Deleted `improve_description.py`, which was responsible for enhancing skill descriptions based on evaluation results.
- Removed `package_skill.py`, the script used for creating distributable `.skill` files from skill folders.
- Eliminated `quick_validate.py`, a minimal validation script for skills.
- Removed `run_eval.py`, which executed trigger evaluations for skill descriptions.
- Deleted `run_loop.py`, the script that combined evaluation and improvement in a loop.
- Removed `utils.py`, which contained shared utilities for the skill creator scripts.

Author: hotlong