fix(test): add delay after template conversion for PVE 9 propagation

PVE 9 may not immediately reflect the template flag in the VM list
after New-PveTemplate returns. Add a 3-second delay before verifying.
PVE 8 passed without the delay.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/PSProxmoxVE.Tests/Integration/Integration.Tests.ps1

@@ -643,6 +643,9 @@ Describe 'Integration Tests' -Tag 'Integration' {
             { New-PveTemplate -Node $script:Node -VmId $script:LinuxVmId -Confirm:$false -ErrorAction Stop } |
                 Should -Not -Throw
 
+            # Allow a moment for the template flag to propagate
+            Start-Sleep -Seconds 3
+
             # Verify it appears as a template
             $templates = Get-PveTemplate -Node $script:Node
             $templates | Where-Object { $_.VmId -eq $script:LinuxVmId } |