Render chat integration readiness as card

[Dkm0315]

Summary

• render /integrations status inside chat as a readable readiness card
• preserve the machine-readable muster integrations status output for shell/script use
• surface score, coverage, blockers, suggested path, channels, packs, MCPs, and guardrails in one chat panel

Validation

• pnpm exec tsx --test packages/cli/test/cli.test.ts
• pnpm --filter @musterhq/cli build
• node packages/cli/dist/index.js chat /integrations status

Notes

This is another chat UX step: it makes readiness understandable without hiding setup blockers or claiming integrations are already configured.