Upkeep is now installable as a Claude Code plugin (/plugin marketplace add wei18/upkeep + /plugin install upkeep@upkeep) or via npx skills add wei18/upkeep --skill upkeep-audit. The GHA reusable workflow is unchanged — @v1 callers keep working but v1 is now frozen; switch to @v2 (identical interface). From now on fixes move the v2 tag only.