chore(scripts): archive PowerShell scripts superseded by the Python CLI

Move 16 .ps1 files to scripts/archived/ — they have no live caller:

- 10 pure shims (New-BuildVM, Remove-BuildVM, Cleanup-OrphanedBuildVMs,
  Wait-VMReady, Invoke-RemoteBuild, Get-BuildArtifacts, Watch-DiskSpace,
  Watch-RunnerHealth, Get-CIJobSummary, Invoke-CIJob) that only forwarded
  to `ci_orchestrator`; the live Gitea composite action now calls
  `python -m ci_orchestrator job` directly.
- 6 Phase-C host tools reimplemented natively in Python (Start-BurnInTest
  [+ -Linux], Test-CapacityBurnIn → bench; Test-Smoke → smoke run;
  Validate-HostState → validate host; Set-CIGuestCredential → creds set).

Add scripts/archived/README.md mapping each file to its `ci` replacement,
and exempt scripts/archived/ from the PSScriptAnalyzer lint job.

Kept (still used / not yet ported): Register-CIScheduledTasks,
Backup-CITemplate, Invoke-RetentionPolicy, Set-TemplateSharedFolders,
Test-CIGuestWinRM, the e2e build harnesses, and all template/ guest
provisioning scripts.

scripts/archived/New-BuildVM.ps1

@@ -0,0 +1,43 @@
+#Requires -Version 5.1
+Set-StrictMode -Version Latest
+$ErrorActionPreference = 'Stop'
+
+# Shim: delegates to the Python ci_orchestrator CLI (`vm new`).
+# Original PS implementation moved to git history; see plans/A3-closeout.md.
+
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory)]
+    [ValidateScript({ Test-Path $_ -PathType Leaf })]
+    [string] $TemplatePath,
+
+    [string] $SnapshotName = 'BaseClean',
+
+    [Parameter(Mandatory)]
+    [string] $CloneBaseDir,
+
+    [Parameter(Mandatory)]
+    [string] $JobId,
+
+    [string] $VmrunPath = 'C:\Program Files (x86)\VMware\VMware Workstation\vmrun.exe'
+)
+
+$pyArgs = @(
+    '--template-path', $TemplatePath,
+    '--snapshot-name', $SnapshotName,
+    '--clone-base-dir', $CloneBaseDir,
+    '--job-id', $JobId,
+    '--vmrun-path', $VmrunPath
+)
+
+$venvPython = $env:CI_VENV_PYTHON
+if (-not $venvPython) {
+    # $IsWindows exists only on PS 6+; absent on PS 5.1 (always Windows)
+    if ($null -ne $IsWindows -and $IsWindows -eq $false) {
+        $venvPython = '/opt/ci/venv/bin/python'
+    } else {
+        $venvPython = 'F:\CI\python\venv\Scripts\python.exe'
+    }
+}
+& $venvPython -m ci_orchestrator vm new @pyArgs
+exit $LASTEXITCODE