X9 onboarding

This package-owned skill owns both installed-skill readiness and the opt-in x9 harness profile; it does not install dependencies, authorize accounts, or edit global agent instructions.

Check only the user-named x9-* skills, or use the current runtime's active skill catalog when the user did not name targets. Resolve every selected skill's physical path against this loaded skill's package skills root. Read a declaration only when its resolved path remains below that root; never read an external path or symlink target. Report an untrusted target as PARTIAL and BLOCKED with that reason. If neither an explicit target nor a safe active catalog is available, report scope as PARTIAL and BLOCKED and ask for skill names rather than scanning directories.