feat: add CLI-style human gates

[ZHOUKAILIAN]

Summary

• upgrade agt2 interactive human gates to show stage summaries and artifact previews
• allow Enter-to-approve and free-text feedback to rework the current Product/Dev plan gate
• add a runtime rework API that records human_rework_requested and injects feedback into the retried stage

Verification

• npm --workspace @agent-team-runtime/runtime run test
• npm run typecheck
• npm run build:packages
• npm test
• npm run build
• PTY smoke: Enter approved Product and Dev gates through to done
• PTY smoke: free-text feedback reworked Product, then approved through to done