Menu screens: rock background, centred frame, logo, 3D hero

- Spielen hero panel shows the selected hero in 3D (cUI_NetGranny,
  game/ui/granny.h).
- All menu screens draw on the options' rock wall; the main menu's 1024
  frame is drawn centred over it, mouse and cursor shifted to match.
- The main menu's and options' own pictures and the main menu's 3D scene
  are left out (textures hidden by surface, scene call redirected).
- Logo top left: FX_SACREDLOGO.TGA, drawn added.
- Game textures by name (game/ui/texture.h), textured and added quads.

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

docs/characters.md

@@ -189,8 +189,16 @@ below; our own background). Built on the shared screen kit
   Its entries are only needed for the load.
 - Left: the characters, newest save first (name, class, level; "im Spiel" for
   the one being played). Click selects, double click plays.
-- Middle: name, class and level, the world played last with its date. (A
-  render of the hero is planned.)
+- Middle: name, class and level, the world played last with its date, and
+  the hero in 3D with its equipment (2026-10-20): the game's cUI_NetGranny
+  (game/ui/granny.h), the control the export screen and the multiplayer
+  lobby showed heroes with. The character's hero file goes to
+  `_workpreview.pax`, LoadHeroFile (path, 0, info) reads its hero info
+  (class, equipment looks) without touching the player hero. Drawn without
+  its name label, with the white light set, size factor 3.8 (game 2.5); its
+  x is moved by (1365 - 1024) / 2, as it centres the model as in a 1024
+  layout. Migrated characters without the shared hero show none until
+  played.
 - Right: a grid campaigns x difficulties. A cell shows the save's date,
   "+ Autosave" when the autosave is newer, "Story abgeschlossen", "Neu" for a
   difficulty that is open but has no world, "–" when closed. Open: Bronze and
@@ -306,5 +314,5 @@ kept, the newest file overall is the shared hero.
 ## Open
 
 - Quickload (row 0) does not know characters (not needed, user 2026-10-20).
-- Spielen screen: a render of the hero; scrolling the list beyond 9 characters.
+- Spielen screen: scrolling the list beyond 9 characters.
 - Multiplayer (see `todo.md`).