Add verification checklist to task completion workflow

When jr worker or human marks a task Done, prompt for verification:

For code tasks:

• [ ] Code compiles (bild succeeds)
• [ ] Tests pass (bild --test)
• [ ] Feature works in production (manual verification)

Options: 1. Add --verified flag to 'task update <id> done --verified' 2. Require 'Review' status before 'Done' (current flow) 3. Add verification notes field

The issue was t-148.x tasks were marked Done when code compiled, but feature didn't work because DB migration wasn't applied.