fix(windows): default to DX12/Vulkan so AMD GL driver can't crash startup (#55)

On some Windows hybrid-GPU laptops the AMD OpenGL driver (atio6axx.dll)
access-violates the instant wgpu enumerates its GL backend at startup,
killing the app before any window appears — even though DX12 works fine.
The crash is inside AMD's proprietary GL ICD, so it can't be fixed
app-side; instead default WGPU_BACKEND to dx12,vulkan on Windows so the
GL ICD is never touched. An explicit user-set WGPU_BACKEND still wins, so
GL remains available via override.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/main.rs

@@ -17,5 +17,14 @@ mod ui;
 mod update_check;
 
 fn main() -> iced::Result {
+    // On some Windows hybrid-GPU laptops the AMD OpenGL driver (atio6axx.dll)
+    // access-violates the moment wgpu enumerates its GL backend at startup,
+    // killing the app before any window appears — even though DX12 would work
+    // fine (#55). Restrict wgpu to DX12/Vulkan so the GL ICD is never touched.
+    // An explicit user-set WGPU_BACKEND still wins.
+    #[cfg(target_os = "windows")]
+    if std::env::var_os("WGPU_BACKEND").is_none() {
+        std::env::set_var("WGPU_BACKEND", "dx12,vulkan");
+    }
     app::run()
 }