Allow version-controlled agent rule files under .claude/rules/ while keeping
machine-local Claude Code state ignored. Aligns with state-hub gitignore pattern.
Extend federation manifest schema for url sources with auth and TTL metadata.
Fetch remote capability indexes over HTTP(S), cache under
registry/federation/cache/, and fall back to stale cache on fetch failure.
Add --refresh flag, seven federation tests, and updated federation docs.
