Setup Matt Pocock Skills

This is the setup step you run once per repo before using Matt Pocock's engineering skills like `triage`, `to-issues`, or `improve-codebase-architecture`. It walks you through three decisions (GitHub vs GitLab vs local markdown for issues, your triage label names, and whether you have one CONTEXT.md or multiple in a monorepo) then writes the config to `docs/agents/` and adds an Agent skills block to CLAUDE.md or AGENTS.md. It's interactive and shows you drafts before writing anything. The nice part is it doesn't assume defaults, it actually reads your .git config and existing files first, so you're not fighting with wrong assumptions later when the other skills try to create issues or read ADRs.