Teleportationstrank: yellow potions open the portal window

- Every yellow potion (potion kind 5, all stages) is a Teleportationstrank:
  drinking it posts the teleporter's event to the busy dialog with the
  hero's known portals; the potion is used up only when the hero teleports
  from that window (closing it keeps the potion)
- Names replaced in every game text (ReplaceInTexts), so item names and the
  bottom bar's quick-select tooltip read Teleportationstrank; GameText reads
  the game's own text
- HeroIndex / HeroInventory moved to skillslots for shared use
- docs/teleport-potion.md; walking animation after loading noted in todo

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

src/game/ui/texts.h

@@ -4,6 +4,7 @@
 // tab headers), and changes to the game's own texts.
 
 #include <cstdint>
+#include <string>
 
 namespace game {
 
@@ -15,4 +16,11 @@ uint32_t RegisterText(const wchar_t* text);
 // "Rucksack"). Call at startup.
 void CapitalizeText(uint32_t id);
 
+// Shows `to` in place of `from` wherever a game text contains it (item names,
+// tooltips, ...).
+void ReplaceInTexts(const std::wstring& from, const std::wstring& to);
+
+// The game's text `id` without our changes (empty if there is none).
+std::wstring GameText(uint32_t id);
+
 } // namespace game