Add verified curl installer bootstrap

[xptea]

Summary

• add a one-line curl.exe installer command to the README
• resolve the latest stable GitHub Release and verify setup against SHA256SUMS.txt before execution
• test checksum rejection, silent installation, PATH lookup, upgrade, and exact uninstall restoration
• publish install.ps1 with release artifacts and bump the release version to 1.1.3

Testing

• .\build.ps1 -Configuration Release -Test
• .\tools\verify-pe.ps1
• .\build.ps1 -Configuration Debug -Test
• .\build.ps1 -Configuration Sanitize -Test -OutputName vgpu-mon-asan
• .\analyze.ps1
• .\package.ps1 -SkipBuild
• .\installer.ps1 -SkipBuild
• .\tests\test_installer.ps1 -InstallerPath .\dist\VGPU-Mon-1.1.3-setup.exe
• live GitHub API plus stdin bootstrap install/uninstall smoke test