ItemTemplate follows ArcItemTemplate_Load (sb.exe 0x4AABD0): weapon and
armor blocks keyed by item type, sheath and stub blocks, and empty equip
slot masks read as empty sets. Adds SheathSlot and readHashLabel, which
keeps unresolved hashes such as item_skill_used in 195340.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
