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>

src/mods/screen.h

@@ -33,6 +33,12 @@ constexpr int kMargin = kFrameOrnament + 16;           // canvas edge to a panel
 constexpr int kPanelGap = 96;  // between two panels' rects, as the options window's columns
 constexpr int kPanelPadding = 16;                      // panel rect to its content
 
+// The logo in the background's top left corner (render target coordinates;
+// screens may overlap it).
+constexpr int kLogoMargin = 48;
+constexpr int kLogoHeight = 124;
+constexpr int kLogoWidth = kLogoHeight * 74 / 100;  // the emblem's aspect (screen.cpp)
+
 constexpr uint16_t kFont = 1;
 constexpr uint32_t kTextColour = 0xffe6d6aa;     // as the options' texts
 constexpr uint32_t kHeadingColour = 0xfff0c060;  // as the options' headings
@@ -41,9 +47,14 @@ constexpr uint32_t kRowColour = 0x40302418;
 constexpr uint32_t kRowHoverColour = 0x80403020;
 constexpr uint32_t kRowSelectedColour = 0xc0604818;
 
+// The background of the menu screens across the whole render target (also
+// beside the main menu's centred frame and full-screen windows in a game).
+void DrawBackground(void* device);
+// Whether a screen is shown (the main menu then does not draw centred).
+bool AnyShown();
+
 // Draws the screen of `window`: the background across the whole render
-// target, then body(context) in canvas coordinates. While `window` is shown
-// the main menu thread renders the full width (widescreen::SetWideMenuScreen).
+// target, then body(context) in canvas coordinates.
 int Render(void* window, void* device, int (*body)(void* context), void* context);
 // Runs body(context) with the event's mouse position in canvas coordinates.
 int Handle(void* event, int (*body)(void* context), void* context);