Windows build fails on Visual Studio 2026 / newer MSVC toolsets (hardcoded VS2022 + toolset)

[exzile]

Describe the bug

The Windows build scripts hardcode Visual Studio 2022 Build Tools and a specific MSVC toolset version, so a machine with only Visual Studio 2026 (v18 / MSVC 14.51) installed cannot build OVMS.

Specifically:

• windows_install_build_dependencies.bat, windows_build.bat, windows_setupvars.bat, and windows_test.bat hardcode C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools, the CMake generator string "Visual Studio 17 2022", and a pinned MSVC toolset version (14.44.35207).
• MSVC 14.51 (VS 2026) raises C5285 ("specializing std::is_signed is forbidden") on TensorFlow/XLA's quantized-type specializations (xla/tsl/framework/type_traits.h). XLA builds with /WX, so it escalates to a fatal C2220 and the build aborts.
• The OpenCV dependency build hardcodes -T v142 (VS 2019 toolset, absent on a VS 2026 box), and newer CMake (4.x) errors out in OpenCV's python auto-detection (find_package called with invalid argument "OFF").
• The openvino dependency link uses mklink /d (symbolic link), which requires SeCreateSymbolicLinkPrivilege (admin / Developer Mode).

Expected behavior

The Windows build should auto-detect the installed Visual Studio edition and MSVC toolset (via vswhere) and build successfully on supported newer toolchains (VS 2022 through VS 2026), without requiring an elevated shell.

Environment

• OS: Windows 11
• Toolchain: Visual Studio 2026 (18.7), MSVC 14.51
• OVMS: 2026.3.0 (built from source)

Fix

Resolved by PR #4328 (vswhere auto-detection of VS edition/generator/toolset, /wd5285 for XLA, OpenCV toolset/python fixes, and mklink /j junction for non-elevated installs).