Widescreen experiment: native render size via dxwrapper, classic menus

- mods/widescreen: redirect the world view's reads of the 1024.0/768.0
  constants and the 3D ortho extents to our variables; render size =
  monitor; relocate the world view's tile draw list (1750 entries, no
  bounds check) into an enlarged object (16384 entries).
- mods/dxwrapper: route DirectDraw through dxwrapper (Dd7to9, D3D9) since
  Windows' D3D7 cannot render to targets larger than 2048; fix the game's
  device info GUID pointer that dxwrapper's enumeration leaves invalid.
  Pinned release fetched by CMake (hash-checked), installed next to the DLL.
- Main menu (UI thread) and loading screen render in a 1024x768 viewport
  and are presented scaled ("classic" layout); in-game uses the full size.
- re/patch: verified code patches (operand redirect, push immediates,
  displacements) and startup hooks; build.ps1/CMake download fixes.

In-game view untested yet; HUD still at the top-left.

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

docs/widescreen.md

@@ -59,6 +59,27 @@ Elsewhere (unknown / UI, leave alone for now): `0x40694a`, `0x4ec036`,
 
 `0x60c1f7`, `0x60da54`, `0x625039`, `0x6283b3`, `0x62858d`, `0x628d3b`.
 
+## Other frame producers (laid out for 1024x768: "classic" frames)
+
+| Address | What | Thread |
+|---|---|---|
+| `0x00756940` | `cUI_Manager` thread loop: main menu (clear, update, BeginScene `0x646f50`, UI render `0x7587b0` incl. the menu's 3D scene, EndScene `0x646fd0`, Flip) | own UI thread |
+| `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 these frames 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.
+
+## Direct3D 7 render target limit
+
+Windows' D3D7 runtime refuses `IDirect3D7::CreateDevice` on any render
+target wider or taller than 2048 (`DDERR_INVALIDOBJECT`, 0x88760082),
+measured with a standalone test: 2048x1440 works, 2049x1440 / 2560x1080 /
+3440x1440 fail. Native ultrawide therefore needs dxwrapper (`Dd7to9`,
+D3D7 -> D3D9), see `src/mods/dxwrapper.cpp`; without it the render size is
+clamped to 2048.
+
 ## Renderer
 
 `DxDriver7::SetDisplayMode` (`0x00645390`) creates back buffer, z-buffer and