Support .agents/skills folder

[alefteris]

In addition to .kilocode/skills/, also consider using .agents/skills/. Or in general, support .agents/ as a place for agent customization files.

For global skills the additional paths should be ~/.agents/skills/ and the XDG location ~/.config/agents/skills/ for Linux.

A lot of other agent tools have already adopted those paths. It will help with onboarding users of other tools to kilo and vice versa, without requiring users to create symlinks or to move files around.

See agentskills/agentskills#15