chore(scripts): archive PowerShell scripts superseded by the Python CLI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/README.md

@@ -0,0 +1,39 @@
+# Archived PowerShell scripts
+
+These `.ps1` files are **frozen** and no longer part of the live pipeline. They
+are kept for history and reference only. Do not call them and do not extend
+them — the production entry point is the Python orchestrator (`ci ...` /
+`python -m ci_orchestrator`).
+
+They are exempt from PSScriptAnalyzer lint (see `.gitea/workflows/lint.yml`).
+
+## Why archived
+
+**Pure shims** — these only forwarded their arguments to the Python CLI. The
+live Gitea composite action (`.gitea/actions/local-ci-build/action.yml`) now
+invokes `python -m ci_orchestrator job` directly, so the shims have no caller.
+
+| Archived shim | Python replacement |
+|---------------|--------------------|
+| `Invoke-CIJob.ps1` | `ci job` |
+| `New-BuildVM.ps1` | `ci vm new` |
+| `Remove-BuildVM.ps1` | `ci vm remove` |
+| `Cleanup-OrphanedBuildVMs.ps1` | `ci vm cleanup` |
+| `Wait-VMReady.ps1` | `ci wait-ready` |
+| `Invoke-RemoteBuild.ps1` | `ci build run` |
+| `Get-BuildArtifacts.ps1` | `ci artifacts collect` |
+| `Watch-DiskSpace.ps1` | `ci monitor disk` |
+| `Watch-RunnerHealth.ps1` | `ci monitor runner` |
+| `Get-CIJobSummary.ps1` | `ci report job` |
+
+**Phase C host tooling** — real PowerShell logic that ran on the Linux host via
+`pwsh`, now reimplemented natively in Python so the Linux host needs no pwsh.
+
+| Archived script | Python replacement |
+|-----------------|--------------------|
+| `Start-BurnInTest.ps1` | `ci bench run` |
+| `Start-BurnInTest-Linux.ps1` | `ci bench run` |
+| `Test-CapacityBurnIn.ps1` | `ci bench run` / `ci bench measure` |
+| `Test-Smoke.ps1` | `ci smoke run` |
+| `Validate-HostState.ps1` | `ci validate host` |
+| `Set-CIGuestCredential.ps1` | `ci creds set` |