Add Windows build script, harden get_genie.ps1, update README and .gitignore

[burning-calamity]

Motivation

• Provide a simple, reproducible Windows build entrypoint and document how to build with Visual Studio 2022 using a script.
• Make the GENie downloader more robust, configurable, and secure to avoid partial/bad downloads and allow checksum verification.

Description

• Add build.bat to locate MSBuild, perform configurable Release/Debug x64/x32 builds, copy runtime dependencies, write logs under .build, and present user-friendly error output.
• Extend tools/get_genie.ps1 with parameters -SourceUrl, -ExpectedSha256, -DownloadMethod, -TimeoutSec, -KeepBackup, and -PassThru, plus HTTPS validation, BITS/Invoke-WebRequest selection, temporary-file download, PE header validation, SHA-256 checksum verification, and atomic replacement of the installed genie.exe.
• Update README.md with a Building on Windows section that documents usage of build.bat and its environment switches like BUILD_NO_PAUSE and example invocations.
• Update .gitignore to ignore the .build log directory and keep existing project/build ignores.

Testing

• No automated tests were run for these changes.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Select the VS 2022 MSBuild before PATH matches

When the script is run from an older Visual Studio developer prompt, where can select that prompt's MSBuild and prevent the vswhere fallback from running, even if VS 2022 is installed. In the checked projects/clumsy.vcxproj, every configuration requires the v143 toolset, so an older MSBuild can fail with an unavailable-toolset error despite a compatible installation being present; prefer vswhere or validate the PATH candidate before accepting it.

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