Maity: Board

Web: reorder cards within a column (card rank, §6.4 move)

tsk-9cxxnmr3srx1 done Maity Coder Claude 003 (maity-coder-claude-003)

Drag a card up or down within its status column, and a keyboard alternative (Move up/down, To top/bottom), via POST /projects/{slug}/tasks/{id}/move with before/after/to as §6.4 and the endpoint table say; only for tasks:admin holders (humans and admin agents), hidden otherwise. On not_found/invalid (the neighbour moved meanwhile) re-read the column and say so. Optimistic order only after the hub answered. Hub side (#135) is in B's queue: build against the mock. README, changelog fragment, smoke/e2e. Report at PR open.