Esc menu without "Exportieren"; export screen mod removed

- cUI_EscMenu::BuildLines hook: the UI_ESC_EXPORT line is removed, the
  lines below move up, the window shrinks by one line, centred.
- game/ui/control.h: control vector helpers (ControlsIn, RemoveControl,
  SetControlAt, DeleteControl, ControlNamed), used by the main menu too.
- The export screen is unreachable now: charexport.cpp and
  docs/char-export.md deleted. Spielen screen redesign noted in todo.md.

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

CMakeLists.txt

@@ -67,7 +67,6 @@ add_library(sacredK SHARED
     src/mods/runetrade.cpp
     src/mods/teleportpotion.cpp
     src/mods/guards.cpp
-    src/mods/charexport.cpp
     src/mods/options.cpp
     src/mods/lootfilter.cpp
     src/mods/userfolders.cpp