item: decorate C_Item.GetItemName location form with random suffix

The location form of C_Item.GetItemName points at a real item instance,
so its name should carry random-suffix decoration ("... of the Owl") the
way modern WoW does -- but we were reading m_name[0] off the itemID-keyed
ItemStats_C cache, which only holds the base name.

Resolve the location to its CGItem and build the name via the engine's
own per-instance name builder (FUN_005D8BC0): it reads the suffix ID off
the descriptor (+0x98) and formats base + ItemRandomProperties localized
suffix through the engine's ITEM_SUFFIX_TEMPLATE. This is the same
builder FUN_GAMETOOLTIP_BUILD_ITEM_LINK wraps in brackets, so the output
now matches GetItemLink's bracketed name and modern C_Item.GetItemName
exactly (verified in-game: "Iridium Chain of the Owl"). Falls back to the
base ItemStats name (and warms the cache) when the instance build yields
nothing.

GetItemNameByID is unchanged -- an itemID has no instance, so base name
only is correct.

src/Offsets.h

@@ -287,6 +287,18 @@ enum Offsets {
     // the item isn't in the player's bag/equipment.
     FUN_GAMETOOLTIP_BUILD_ITEM_LINK = 0x0052AE00,
 
+    // CGItem → decorated instance display name. __thiscall(ecx = CGItem *,
+    // char *outBuf, uint outSize). Reads the instance's random-suffix ID
+    // off the descriptor (+0x98, gated on the broken flag) and writes the
+    // plain — uncolored, unbracketed — display name into outBuf:
+    // "Ethereum Torque of the Sorcerer" when a suffix is present, the base
+    // ItemStats name otherwise (via the item cache + ItemRandomProperties
+    // localized suffix at record +0x1c). This is the inner name builder
+    // FUN_GAMETOOLTIP_BUILD_ITEM_LINK wraps in brackets, so the name it
+    // produces matches GetItemLink's bracketed name and modern
+    // C_Item.GetItemName exactly. Inner formatter FUN_005D8B00.
+    FUN_ITEM_BUILD_INSTANCE_NAME = 0x005D8BC0,
+
     // Engine's inventory swap-and-send. Same primitive
     // `Script_EquipCursorItem` (0x00489660) uses after the cursor's
     // source location has been resolved. Sends opcode 0x10D

src/item/Name.cpp

@@ -56,18 +56,51 @@ int PushNameForItemID(void *L, int itemID) {
     return 1;
 }
 
+// Engine's per-instance item-name builder: `__thiscall(CGItem *this,
+// char *outBuf, uint outSize)`. Reads the instance's random-suffix ID off
+// the descriptor (+0x98) and writes the decorated display name
+// ("Ethereum Torque of the Sorcerer"), or the base name when there's no
+// suffix. Same builder the item-link builder uses for the bracketed name,
+// so this matches `GetItemLink`'s name and modern `C_Item.GetItemName`.
+using BuildInstanceName_t = void(__thiscall *)(const void *cgItem, char *out,
+                                               unsigned outSize);
+
+// Pushes the suffix-decorated display name for a resolved `CGItem`.
+// Returns 0 (pushes nothing) for a null item or an empty build result,
+// so the caller can fall back to the base-name-by-itemID path.
+int PushInstanceName(void *L, const uint8_t *cgItem) {
+    if (cgItem == nullptr)
+        return 0;
+    char buf[128];
+    buf[0] = '\0';
+    auto fn = reinterpret_cast<BuildInstanceName_t>(
+        Offsets::FUN_ITEM_BUILD_INSTANCE_NAME);
+    fn(cgItem, buf, sizeof(buf));
+    if (buf[0] == '\0')
+        return 0;
+    Game::Lua::PushString(L, buf);
+    return 1;
+}
+
 } // namespace
 
-// `C_Item.GetItemName(itemLocation)` — returns the cached display name
-// of the item at the location, or nil for empty / uncached / invalid
-// inputs. Reads `m_name[0]` straight off `ItemStats_C` — no engine
-// round-trip, no `GetItemInfo` chaining.
+// `C_Item.GetItemName(itemLocation)` — returns the display name of the
+// item at the location, or nil for empty / uncached / invalid inputs.
+// The location points at a real item instance, so the name carries any
+// random-suffix decoration ("... of the Sorcerer") — built off the
+// CGItem via the engine's own name builder, matching modern WoW and
+// `C_Item.GetItemLink`'s bracketed name. Falls back to the base
+// `ItemStats_C` name (and warms the cache) if the instance build yields
+// nothing.
 static int __fastcall Script_C_Item_GetItemName(void *L) {
     if (!Item::Location::IsLocationArg(L, 1)) {
         Game::Lua::Error(L, "Usage: C_Item.GetItemName(itemLocation)");
         return 0;
     }
-    return PushNameForItemID(L, Item::ID::FromCGItem(Item::Location::Resolve(L, 1)));
+    const uint8_t *cgItem = Item::Location::Resolve(L, 1);
+    if (int pushed = PushInstanceName(L, cgItem))
+        return pushed;
+    return PushNameForItemID(L, Item::ID::FromCGItem(cgItem));
 }
 
 // `C_Item.GetItemNameByID(itemInfo)` — returns the cached display name