Add rico multi-agent Slack runtime

[xogjs]

Summary

• add the rico runtime scaffold, SQLite workflow store, Slack ingress queue, governor/captain orchestration, role memory, artifact publishing, and approval gates
• add end-to-end happy path coverage plus focused tests for config, store, runner, Slack routing, specialist isolation, artifact publishing, and approval handling
• add the Korean rico design/implementation docs plus operator docs in rico/README.md

Test Plan

• bun test rico/test/
• bun run dev:rico