2026 01 09 Support Using Ai Features Tables Improve Prompts

<!-- entry: {"id":"2026-01-09-28-1-ai-api-upgrade-copied-command-routes-1306d0ec","kind":"behavior","migrationNotes":[]} -->

• ai-api, ai-menu, use-chat: Upgrade copied AI command routes and chat UI for AI SDK v6 with split prompt helpers and table-cell editing prompts.

<!-- entry: {"id":"2026-01-09-28-1-cursor-overlay-sync-behavior-ai-sdk-f014616f","kind":"behavior","migrationNotes":[]} -->

• cursor-overlay: Sync cursor overlay behavior with the AI SDK v6 interaction path.