Characters: one file per character with a world per difficulty

- CharacterNN.sacredK holds the shared hero and one world per difficulty,
  plus an autosave file; the game works in save\characters\_work
- Load window: one row per character, a difficulty dialog on Laden
  (worlds, newer autosaves, "(neu)" starts a new game with the shared
  hero), Umbenennen, delete moves the character to characters\deleted
- The world keeps its own portals and hero position when the shared hero
  is put on
- K and the Esc menu's "Speichern" save directly (quicksave path)
- One-time migration of the old save rows and exported heroes, after a
  backup
- Startup no longer hangs in the game's foreground loop (0x810af0)
- Text overrides apply to our own text ids too; shared cUI_Button2
  helpers in game/ui/button.h

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

src/mods/hud.cpp

@@ -695,8 +695,7 @@ HUD_RENDER(0x006f73f0, UiNetworkInfo_Render, Anchor::Center)
 HUD_EVENT(0x0070e860, UiCharacter_HandleEvent, Anchor::Center)
 HUD_RENDER3_FRAMED(0x0070f160, UiCharacter_Render)  // export screen in-game
 // cUI_Options (0x716b30 / 0x716640): hooked by mods/options.cpp.
-HUD_EVENT(0x0071d130, UiSavegame_HandleEvent, Anchor::Center)
-HUD_RENDER_FRAMED(0x0071dd80, UiSavegame_Render)
+// cUI_Savegame (0x71d130 / 0x71dd80): hooked by mods/characters.cpp.
 HUD_EVENT(0x00720c10, UiBusyDlg_HandleEvent, Anchor::Center)
 HUD_RENDER(0x007213a0, UiBusyDlg_Render, Anchor::Center)