powershell installer picks the wrong architecture

[zsol]

On an arm64 Windows host, running

> powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
Downloading uv 0.8.15 (x86_64-pc-windows-msvc)

As you can see, it picks an x86_64 release to download & install.

After some digging, it seems like this logic:

$a = [System.Reflection.Assembly]::LoadWithPartialName("System.Runtime.InteropServices.RuntimeInformation")
$t = $a.GetType("System.Runtime.InteropServices.RuntimeInformation")
$p = $t.GetProperty("OSArchitecture")
$p.GetValue($null)

Returns X64 when executed via powershell.exe. It returns the correct value from Powershell Core (aka pwsh.exe), and indeed:

> pwsh -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
Downloading uv 0.8.15 (aarch64-pc-windows-msvc)

version info:

> powershell -c 'echo $PSVersionTable'

Name                           Value
----                           -----
PSVersion                      5.1.26100.5074
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.26100.5074
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

> pwsh -c 'echo $PSVersionTable'

Name                           Value
----                           -----
PSVersion                      7.5.0
PSEdition                      Core
GitCommitId                    7.5.0
OS                             Microsoft Windows 10.0.26100
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0