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/mods/skillslots.cpp

@@ -21,6 +21,9 @@
 
 #include <windows.h>
 
+#include "game/engine/items.h"
+#include "game/engine/objects.h"
+#include "game/engine/orders.h"
 #include "re/hook.h"
 
 namespace mods::skillslots {
@@ -51,6 +54,17 @@ uint8_t* Inventory(unsigned index) {
     return base && index < kInventories ? base + index * kInventorySize : nullptr;
 }
 
+int HeroIndex() {
+    void* hero = game::GetPlayerHero();
+    const int index = hero ? game::CreatureField(hero, game::kCreatureId) : -1;
+    return index >= 0 && index < game::kChestInventory ? index : -1;
+}
+
+uint8_t* HeroInventory() {
+    const int hero = HeroIndex();
+    return hero >= 0 ? Inventory(static_cast<unsigned>(hero)) : nullptr;
+}
+
 uint8_t* ShadowFor(const void* inventory, bool create) {
     const int index = IndexOf(inventory);
     if (index < 0) {