feat(prepare-win): add --gui/--nogui flag, default headless

Lets `template prepare-win` start the template VM in the Workstation
window (--gui) for interactive debugging; defaults to headless --nogui.

src/ci_orchestrator/commands/template.py

@@ -386,6 +386,9 @@ def _run_with_heartbeat(
               help="Keyring target name for the stored credential.")
 @click.option("--recreate-snapshot", is_flag=True,
               help="Delete and recreate the snapshot if it already exists (no prompt).")
+@click.option("--gui/--nogui", "gui", default=False, show_default=True,
+              help="Start the VM with the Workstation window (--gui, needs an X display) "
+                   "or headless (--nogui, the default).")
 def template_prepare_win(
     vmx: str,
     guest_ip: str,
@@ -403,6 +406,7 @@ def template_prepare_win(
     store_credential: bool,
     credential_target: str,
     recreate_snapshot: bool,
+    gui: bool,
 ) -> None:
     """Provision a Windows template VM via pypsrp (Linux-host compatible).
 
@@ -466,8 +470,9 @@ def template_prepare_win(
     handle = VmHandle(identifier=str(vmx_path), name=vmx_path.stem)
 
     if not backend.is_running(handle):
-        click.echo(f"[prepare-win] Starting VM: {vmx_path.name} ...")
-        backend.start(handle, headless=True)
+        mode = "GUI" if gui else "headless"
+        click.echo(f"[prepare-win] Starting VM ({mode}): {vmx_path.name} ...")
+        backend.start(handle, headless=not gui)
     else:
         click.echo(f"[prepare-win] VM already running: {vmx_path.name}")