Tighten scope by spinning out packages unrelated to hook installation + enforcement

[4meta5]

Extract skills packages unrelated to hook installation + enforcement into new project skillex

skillex

1. open source + publish packages from new repo with new repo link after migrating + cut release with changelog
2. make issue for new package: skill-repl
3. make issue for new package: skill-search which implements external skill search NOT related to skill-cli list/scan
4. make issue for new package: skill-sota which stores skill sota conventions to suggest updates to skills or even merging/splitting them for better discovery and usage

hooks

1. publish packages after extracting skillex stuff + cut release with changelog + reference skillex from readme + update skills readme to also reference skillex and update the hooks reference claims
2. make issue for exploring/extending this new leaner project with plugins + testing for when to prefer hooks vs plugins
3. make issue for exploring optimal enforcement architecture for pi agent extensions
4. make issue for exploring layering hooks and/or plugins in an optimal way
5. make issue to remove usage tracker hook and extract it into skillex tools for tracking skill + skill enforcement metrics but in a global way that ideally interoperates with improving skills/ hooks/ and skillex/