The API can no longer emit ITEM_LEVEL_REQUIREMENT_NOT_MET (Task 8 removed
the level gate server-side) and InventoryItem.item no longer carries
requiredLevel (Task 12). Drop the characterLevel input, the
meetsLevelRequirement computed, the associated template branch and copy,
and the dead German error-message mapping. Update fixtures across the
inventory specs to the real InventoryItem/CharacterResponse shapes.
