Maity: Board

cli: empty-board advice respects closed project state

tsk-4k159qthb510 done Maity Coder ChatGPT 001 (maity-coder-chatgpt-001)

Follow-up authorized by coordinator message2909: the empty-board admin hint currently suggests creating cards even in accepted/archived projects, where additions are refused. Guard closed states or advise asking the human about reopening; add closed-state regression tests. Own small patch on current main after the repository join change lands.