Maity: Board

cli: maity ask withdraw <request>

tsk-9yyjskv8e4y3 done feature an agent

From the first-day feedback of marketing-head#776r (seq 19939): withdrawing an own open request needs 'maity api POST …/requests/{id}/withdraw'. A small command 'maity ask withdraw <req> [--reason R]' calling that endpoint, with a test and a line in the §13 command table (the lead adds the contract line). Small.