chore: add Agent Skills (#9515)
* add script to generate agent skills
* init agent skills
* remove generated rules
* output to .well-known
* clean up script
* Revert "remove generated rules"
This reverts commit 62b228322499d4c7edd03b2cccb9a375609648b3.
* remove generated skills from repo
* explicitly move .well-known in build-s2-docs
* remove truncation from lists in SKILLS.md
* add docs (consolidate with mcp docs)
* review comments
