agent-team v0.6.1

Added

• The product vision: VISION.md tells the team what the product should be. Every workflow
  receives it with the README, and discuss gives it its own section, so the roadmap is planned
  towards it. init asks for it first (or --vision TEXT|FILE); discuss --vision FILE plans from
  a file anywhere and saves it as VISION.md when there's none. /team-init and /team-plan ask
  for it when it's missing.

Changed

• discuss no longer needs a topic: the default is "next milestones".