add extra env variable to support winget installation

[dtrawins]

🛠 Summary

JIRA/Issue if applicable.
Describe the changes.

🧪 Checklist

• Unit tests added.
• The documentation updated.
• Change follows security best practices.
  ``

[Copilot]

Pull request overview

This PR updates the Windows entrypoint to initialize OPENVINO_TOKENIZERS_PATH_GENAI automatically when OVMS is deployed as an MSIX/winget package, by discovering the OpenVINO Tokenizers dependency package and deriving the DLL path from its installed location.

Changes:

• Added C++/WinRT package dependency inspection to locate the Tokenizers MSIX dependency.
• Set OPENVINO_TOKENIZERS_PATH_GENAI based on the dependency’s InstalledLocation at process startup.
• Introduced a new WinRT header include to support the dependency query.

Comments suppressed due to low confidence (2)

src/main_windows.cpp:118

• This code uses C++/WinRT APIs (Package::Current()...) but the thread apartment is never initialized (no winrt::init_apartment() found). Without initialization, WinRT calls can fail and the env var will not be set even in packaged deployments.

    try {
        winrt::Windows::Foundation::Collections::IVectorView<winrt::Windows::ApplicationModel::Package> deps =
            winrt::Windows::ApplicationModel::Package::Current().Dependencies();
        for (const winrt::Windows::ApplicationModel::Package& dep : deps) {

src/main_windows.cpp:123

• This unconditionally overwrites OPENVINO_TOKENIZERS_PATH_GENAI, which can clobber a user- or admin-provided setting. Prefer only setting it when it is not already defined, and consider logging/handling a failure return from SetEnvironmentVariableW.

                SetEnvironmentVariableW(L"OPENVINO_TOKENIZERS_PATH_GENAI", dllPath.c_str());
                DEBUG_LOG("OPENVINO_TOKENIZERS_PATH_GENAI initialized from package dependency.");
                return;