Map: zoomed-view symbols centred, 10x reveal and enemy range; progress screen on the menu background

- Megamap / TAB map zoomed view: heroes' markers and the other symbols
  (integer 200h centre immediates) follow the view's centre.
- Map reveal: the hero's reveal stamp scaled 10x (mods/mapreveal.cpp,
  docs/map-reveal.md); creatures on the zoomed map shown within 10x the
  sight range.
- Load / save progress screen drawn on the rock background across the full
  width, the picture blended over it (mods/loadingscreen.cpp); the classic
  1024x768 frame is gone.

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

docs/widescreen.md

@@ -67,9 +67,10 @@ Elsewhere (unknown / UI, leave alone for now): `0x40694a`, `0x4ec036`,
 | `0x006469d0` | loading screen: GDI BitBlt of bitmap + progress bar + text into the back buffer (fixed 1024x768) | render thread |
 | `0x006a0c60` | video/intro playback (unexamined) | |
 
-The widescreen mod gives the loading screen a 1024x768 D3D viewport (set at
-`BeginScene` when the scene depth `+0x1d8` is 0) and the borderless mod
-presents only that area, scaled to the monitor. The main menu thread renders
+Since 2026-10-25 the loading screen uses the full render width too: the menu
+background is drawn across it and the game's GDI drawing is centred
+(mods/loadingscreen.cpp, docs/screens.md "Load / save progress screen"); the
+1024x768 "classic" viewport and present are gone. The main menu thread renders
 the full width since 2026-10-20: its 1024x768 frame is drawn centred on the
 menu screens' background (docs/screens.md, "Main menu frame").