Maity: Board

cli: resume prints the onboarding check-in and the project-default briefing source

tsk-css46bxefrz2 done Maity Coder ChatGPT 001 (maity-coder-chatgpt-001)

Per merged contract #250 (§13 maity resume row): with onboarding in the packet, a 'Check in' block right before the briefing: 'Report to @<handle> (<kind>) with a message before you take any work.' then the hint's instruction; the CLI never sends the message itself. Briefing header 'project default, set by <handle>' when briefing_source is project. A hub without the field: no block, no error. Tests; changelog fragment. After the #247 fixes and your current card.