Completes the SRD standard-action suite. Off-hand attack reuses the
normal hit math with only the damage expression swapped, positive
ability mod withheld per SRD (negative kept), Light property modeled
explicitly (opt-in on stat blocks; undeclared weapons refused, never
silently permitted), and a new spend_bonus_action enforcement point —
plus SRD ordering (Attack action must already be spent). Help stores a
consumable advantage promise ON THE BENEFICIARY, consumed exactly once
by same-side attackers through both attack routes, cleared on refresh,
and rewound with Action refund. Ledger + gateway proxies + client
helpers throughout; seed never client-forwardable. 18 red-first tests;
228 workspace / 476 pytest green, clippy -D clean.
Co-Authored-By: Claude <[email protected]>
