Windows: start Direct3D 12 first, and Vulkan only without a D3D12 GPU (#1190)

* Windows: start Direct3D 12 first, and Vulkan only without a D3D12 GPU

wgpu started Vulkan, D3D12 and OpenGL together and preferred Vulkan, so
every Windows start loaded all installed Vulkan drivers. An old Intel
Vulkan driver (igvk64.dll) crashed 0.10.1 at startup inside the driver.

The app now probes D3D12, then Vulkan, then OpenGL, one backend at a
time, and starts only the first with a hardware adapter (WARP when none
has one). WGPU_BACKEND still wins; graphics.json's "backend" sets the
order by hand; the software renderer (safe mode, the retry) uses D3D12
alone. A new Windows CI job starts the real app under several settings.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* CI: a test filter YAML parses

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* CI: the startup smoke test writes graphics.json where the app reads it

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* CI: run the WARP shader tests one at a time

WARP's shader JIT (d3d10warp.dll) crashed twice in 124 runs of the gpu
tests with four test threads, with a null read inside its own optimizer
while several devices compiled compute pipelines at once. Serial runs
did not crash.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

---------

Co-authored-by: Claude Opus 5.5 <[email protected]>

docs/book/src/guide/troubleshooting.md

@@ -62,6 +62,28 @@ saying what failed (earlier versions closed without a word). Things to try:
 - Run `solidcraft --crash-log` to list recent crash reports, and attach the newest one to an
   issue.
 
+## SolidCraft closes right away on Windows
+
+A graphics driver can crash the app while it starts, before SolidCraft can show anything (an
+old Intel Vulkan driver, `igvk64.dll`, did). Windows' Event Viewer names the driver under
+*Windows Logs › Application* ("Faulting module name").
+
+From 0.11.1, SolidCraft on Windows starts Direct3D 12 first and loads no other graphics API
+when Direct3D 12 has a graphics card; Vulkan and then OpenGL are tried only on a computer
+without one. Earlier versions started Vulkan, Direct3D 12 and OpenGL together and preferred
+Vulkan. To choose the graphics API yourself, in any version, open a Command Prompt and start
+SolidCraft from it:
+
+```
+set WGPU_BACKEND=dx12
+"C:\Program Files\SolidCraft\solidcraft.exe"
+```
+
+`vulkan` and `gl` are the other choices. `setx WGPU_BACKEND dx12` keeps it for apps started
+from the Start menu after you sign in again. From 0.11.1 the setting can also live in
+`graphics.json` in the settings folder, as `{"msaa": 4, "backend": "dx12"}` (`auto` is the
+order above). Safe mode ignores it and always uses the software renderer.
+
 ## A design saved by 0.10 won't open in an older version
 
 Designs saved by a newer SolidCraft use a newer file format. Older versions refuse them with