Fix remaining lint and flaky prerelease download

- add comment help/output metadata in Verify-InstalledVersion helper functions so super-linter PowerShell checks pass
- add bounded retry loop around Windows MSI Invoke-WebRequest to reduce transient prerelease job failures

Author: MariusStorhaug

scripts/windows/install.ps1

@@ -147,7 +147,25 @@ $msi = "PowerShell-$($env:REQUESTED_VERSION)-win-x64.msi"
 $url = "https://github.com/PowerShell/PowerShell/releases/download/v$($env:REQUESTED_VERSION)/$msi"
 Write-Host "Downloading from: $url"
 
-$null = Invoke-WebRequest -Uri $url -OutFile $msi -UseBasicParsing -ErrorAction Stop
+$downloadSucceeded = $false
+$maxAttempts = 3
+for ($attempt = 1; $attempt -le $maxAttempts; $attempt++) {
+    try {
+        $null = Invoke-WebRequest -Uri $url -OutFile $msi -UseBasicParsing -ErrorAction Stop
+        $downloadSucceeded = $true
+        break
+    } catch {
+        if ($attempt -eq $maxAttempts) {
+            throw
+        }
+        Write-Host "Warning: Download attempt $attempt failed; retrying..."
+    }
+}
+
+if (-not $downloadSucceeded) {
+    Write-Host 'Error: Failed to download PowerShell package after retry attempts.'
+    exit 1
+}
 
 # Install requested version
 Write-Host "Starting installation of PowerShell [$($env:REQUESTED_VERSION)]..."

tests/scripts/Verify-InstalledVersion.ps1

@@ -9,8 +9,13 @@ param(
     [string] $GitHubToken
 )
 
+<#
+.SYNOPSIS
+Builds GitHub API request headers for optional authenticated requests.
+#>
 function Get-GitHubApiHeader {
     [CmdletBinding()]
+    [OutputType([hashtable])]
     param(
         [Parameter()]
         [string] $Token
@@ -28,8 +33,13 @@ function Get-GitHubApiHeader {
     return $headers
 }
 
+<#
+.SYNOPSIS
+Resolves symbolic input values (latest/prerelease) to a concrete PowerShell version.
+#>
 function Resolve-ExpectedVersion {
     [CmdletBinding()]
+    [OutputType([string])]
     param(
         [Parameter(Mandatory)]
         [string] $Version,