feat(cli): invokable skills and import any skill (#11113)

* list all skills using /skills slash command

* make skills slash command invokable

* load the skill using skills tool

* make skills tool allowed by default

* add /import-skills slash command

* Update extensions/cli/src/tools/skills.ts

Co-authored-by: cubic-dev-ai[bot] <191113872+cubic-dev-ai[bot]@users.noreply.github.com>

* fix stale in use effect

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Co-authored-by: cubic-dev-ai[bot] <191113872+cubic-dev-ai[bot]@users.noreply.github.com>
Co-authored-by: Dallin Romney <dallinromney@gmail.com>