Characters: 16:9 "Spielen" screen, autosave interval option

- Shared screen kit (mods/screen, docs/screens.md): a 1365x768 canvas
  centred in the render width on our own dark background, the game's
  frames and buttons; the main menu renders full width while it is shown.
- The load window (cUI_Savegame) is replaced by the Spielen screen:
  character list, hero panel, campaign x difficulty grid, save/autosave
  choice, rename/delete/reset/new character dialogs.
- Migrated characters without a shared hero load their hero's world
  first, then start the new world.
- Options, Allgemein: autosave interval (Aus/5/10/15/30 minutes).

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

docs/options.md

@@ -117,3 +117,18 @@ choice (PICKUPAUTO radio buttons, their labels, the separator; matched by
 pointer and control name at +0x30) is never shown, a framed table below the
 auto-pickup frame sets a mode per category. Its frame is made like the key
 page's (`AddFrame`).
+
+## Allgemein: autosave interval (2026-10-20)
+
+Request: the silent autosave's interval (docs/characters.md, Save) settable
+in the options, not only in `sacredK.ini`. The general frame moved up into
+the auto-pickup frame's place; it is taller than the frames beside it, so the
+new frame goes below the lowest frame of the left column. It copies the
+right column's lowest frame (Internet-Optionen): its height and the gap the
+right column leaves between its frames, measured from the window's frames
+when it is made (a lower frame broke its side ornaments, a smaller gap joined
+the borders: screenshots 2026-10-20). One row *Autosave (Min.)*: Aus / 5 /
+10 / 15 / 30 (the key page's box colour is not seen on the dark backdrop: a
+lighter one). A click selects, OK writes
+`[characters] AutosaveMinutes` (`characters::SetAutosaveMinutes`, the timer
+uses it at once), Cancel drops it.