ops(on-snolla): rename site alias on->internal (admin at internal.snolla.com/admin)

- Sites.Alias+LoweredAlias on->internal (siteId B9ECDB50; PrimaryDomain on.snolla.com kept).
- Web.config primaryAlias on->internal (catch-all default-site; without it the whole
  catch-all NRE-500s on every request — primaryAlias references the renamed alias).
- hosts: on.snolla.com->internal.snolla.com under # snolla-local-admin marker.
- setup-local-snolla-admin.ps1 aliases array updated.
- runbook + NEXT_SESSION + memory updated.

VDS prod on.snolla.com unaffected (snolla-app uses config.siteId, not alias) — verified
byte-identical + smoke GREEN after rename. Incident: elevated hosts edit emptied hosts
to 0B (Get-Content -Raw returned null in RunAs context) — restored from Windows default
header + snolla-local-admin block. Memory snolla-catch-all-primaryalias-depends-on-alias.

Co-Authored-By: Claude <noreply@anthropic.com>

scripts/local-snolla-admin-restore/setup-local-snolla-admin.ps1

@@ -11,7 +11,7 @@ Import-Module WebAdministration
 $siteName = 'snolla'
 $poolName = 'snolla'
 $physPath = 'C:\sites\snolla'
-$aliases = @('tandemmebel.snolla.com','labtools.snolla.com','labtoolspro.snolla.com','emspb.snolla.com','kupimknigi.snolla.com','on.snolla.com')
+$aliases = @('tandemmebel.snolla.com','labtools.snolla.com','labtoolspro.snolla.com','emspb.snolla.com','kupimknigi.snolla.com','internal.snolla.com')
 
 Write-Host "== 1. AppPool $poolName =="
 if (Test-Path "IIS:\AppPools\$poolName") {