Potion counts on the bottom bar and potion stacks in the inventory

- potioncounts.cpp: each potion slot shows how many potions of its kind the
  hero carries (stacks added up)
- potionstack.cpp: potions of one type stack up to 20 per cell; every
  potion entering the hero's grid pours into stacks with room, the sort
  button stacks first, drinking takes one off a stack, counts drawn on the
  cells and saved in the JSON inventories
- game/engine/items.h: potion kinds and grid helpers; ObjectManager and
  DestroyObject in objects.h
- auto-attack: the projectile-weapon target radius is a design value
- docs/potion-stacks.md: measured paths and the design

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tools/names.txt

@@ -102,6 +102,24 @@
 0x005dd9f0 cInventoryEntry::Serialize          # (stream, write)
 0x005de8a0 cInventoryEntry::FixInventory
 0x005da880 cInventoryEntry::GetPotionRef
+0x0043f630 ItemPotionKind                  # (ecx = item type table *0xaa9564, type): potion kind 1-5, 0 = none
+0x006e39e0 cUI_Taskbar2::RenderPotionSlots  # 5 potion kinds, controls at +0x258 (stride 0xbc)
+0x005d9ec0 cInventoryEntry::PlaceItem      # (cell, id, w, h, notify) -> network 0x13f; returns the item it replaced
+0x005da290 cInventoryEntry::GetItemAt      # (cell, resolve covered cells)
+0x005da360 cInventoryEntry::CountItems
+0x005da390 cInventoryEntry::RemoveAt       # (cell, notify) -> network 0x13e
+0x005da5f0 cInventoryEntry::RemoveItem     # (id, notify)
+0x005dab60 cInventoryEntry::FindFreeSpace  # (w, h, out cell, mode)
+0x005dac70 cInventoryEntry::FitsAt         # (cell, w, h)
+0x005db670 cInventoryEntry::Sort           # (mode): the inventory window's sort button, trader stock
+0x005dc3f0 cInventoryEntry::DrawItems      # (renderer, flag)
+0x005dd530 cInventoryEntry::CellRect       # (out rect, cell): 32x32 from the origin at +0x1164 / +0x1166
+0x0054a8f0 cCreature::UseItem              # (id): event 0x10 to the item; used up -> RemoveItem + DestroyObject
+0x005fbe10 cObjectManager::DestroyObject   # (id, 1, 0, 0)
+0x005ca9d0 cPotion3D::ReceiveEvent         # vf18: drink effect, sets +0x14 bit 0x8000000 (used up)
+0x00613040 cEngine::UseActionSlot          # (potion kind, ...): potion keys
+0x006c5f40 cUI_Inventory3::HandleEvent     # sort button (+0x158) -> cInventoryEntry::Sort
+0x006c1210 cUI_InventoryTab::Render        # grid origin (0, 0x188), DrawItems
 0x0057f750 SlotCountForLevel                   # table 0x95503c, max 5
 0x008110d0 GameWindowProc                    # in-game window procedure: keys (dead keys, modifiers 0x182cdec)
 0x005def60 cInventoryManager::Serialize      # (stream, write, x): all 32 inventories, save games