Symlink all skills individually into .agents/skills during installation #163

As more and more repositories start adopting new standards, it's important to play nicely with pre-existing agents and skills.

.agents folder appears to be the new cross agent standard for storing skills: https://cursor.com/docs/skills#skill-directories

I recommend that we symlink all of our skills into the .agents folder such that .agents/skills/aidd-* all points to ai/skills/aidd-*

Behavior should be:

• create .agents/skills folders if they do not exist.
• symlink all our aidd-* skills into it
• if any aidd-* skills are present and not symlinks then we do not modify them. This would allow consumers to effectively override and disable an aidd- skill they didn't want.