Code review nit-fix on top of d3b58c9 — addresses two issues from the
quality review of Task 1:
I1 (Important): the record struct `Shortcut` was a homograph with the
flag member `CharacterOptionDataFlag.Shortcut`. Both names live inside
`PlayerDescriptionParser`'s scope. Rename to `ShortcutEntry` aligns
with `InventoryEntry`/`EquippedEntry` and removes the trap before
Task 3's walker references both names in the same method body.
M2 (Minor): `EquippedEntry` had no holtburger source citation; added
one referencing events.rs:180-190. Also expanded `InventoryEntry`'s
comment with the strict reader's validation reference.
Plan doc updated in lockstep so Task 3+ implementers see the new name.
8/8 PlayerDescriptionParser tests still pass.
