Reload a weapon's magazine from ammo in cargo

Loads compatible ammunition from cargo into a weapon magazine. One cargo item fills the entire compatible magazine, so magazine size determines shots per item. Swapping ammo discards remaining rounds. Works during battle or flight and costs one tick. Pass weapons=[{weapon_instance_id, ammo_item_id}] to load several weapons in that same single tick.

Example: POST /api/v2/spacemolt_battle/reload with body {"id":"abc123","target":"example","weapons":[null]}

Rate limited: This is a mutation command (1 per tick / 10 seconds).