add pending approvals a2ui reply

[dnbrwstr]

Summary

Adds an A2UI card response for /pending when there are a small number of active approval requests. Larger pending lists keep using the existing text output.

Changes

• build a pending approvals A2UI card with per-request actions
• return either text or UI data from the /pending command path
• pass reply blobs through the monitor delivery path
• add coverage for pending approval card generation and command auth plumbing

How did I test?

• pnpm test src/monitor/approval.test.ts src/monitor/command-auth.test.ts

[patosullivan]

Migrated to the tlon-apps monorepo: tloncorp/tlon-apps#5939 (cherry-picked onto the rebased a2ui stack, relocated to packages/openclaw). Closing in favor of that PR.