Patch release on top of 1.6.0:

  - Three-pillar Welcome card (Layered modeling · Git-native · AI-ready)
  - New 'Docs' onboarding step (auto-generated docs view of imported project)
  - Refreshed validation step copy mentioning the new red/yellow/green dot
  - JOURNEY_VERSION bumped 1 → 2 to re-trigger for existing users
  - validation:opened event now actually emitted (was dead-coded)