fix(template): move snapshot conflict check to pre-flight (before WinRM)

pypsrp alters terminal tty state during remote sessions. Any readline()
call after WinRM work receives \r instead of \n on Enter (terminal in
raw mode), causing the prompt to spin printing ^M and never return.

Fix: check for existing snapshot and ask the user at the very beginning
of the command, before any WinRM/pypsrp connections are opened, when the
terminal is still in canonical mode. If the user declines, abort early.
At the end, if the snapshot still exists (race-safe), delete silently
and recreate — no second prompt needed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ci_orchestrator/commands/template.py

@@ -432,10 +432,26 @@ def template_prepare_win(
     if not build_password:
         build_password = click.prompt(f"New {build_username} password", hide_input=True)
 
-    # --- Backend: start VM and detect IP ---
+    # --- Pre-flight snapshot conflict check (terminal still clean here) ---
+    # Must happen before any WinRM/pypsrp calls, which alter tty state and
+    # prevent readline() from receiving \n on Enter.
     config = load_config()
     backend = WorkstationVmrunBackend(vmrun_path=config.vmrun_path)
     handle = VmHandle(identifier=str(vmx_path), name=vmx_path.stem)
+    existing_snapshots = backend.list_snapshots(handle)
+    do_recreate_snapshot = True
+    if snapshot in existing_snapshots:
+        click.echo(f"[prepare-win] Snapshot '{snapshot}' already exists.")
+        if recreate_snapshot:
+            click.echo(f"[prepare-win] --recreate-snapshot set: will delete and recreate.")
+        else:
+            sys.stdout.write(f"[prepare-win] Delete and recreate '{snapshot}'? [y/N] ")
+            sys.stdout.flush()
+            raw = sys.stdin.readline()
+            do_recreate_snapshot = raw.strip().lower() in ("y", "yes")
+        if not do_recreate_snapshot:
+            click.echo("[prepare-win] Keeping existing snapshot. Provisioning aborted.")
+            return
 
     if not backend.is_running(handle):
         click.echo(f"[prepare-win] Starting VM: {vmx_path.name} ...")
@@ -664,22 +680,10 @@ Register-ScheduledTask -TaskName 'CI-StaticIp' `
         raise click.ClickException("VM did not power off within 120s.")
     click.echo("[prepare-win] VM powered off.")
 
-    # Create snapshot
+    # Create snapshot — conflict already resolved at pre-flight above.
     vmrun_exe = backend.vmrun_path
-    existing = backend.list_snapshots(handle)
-    if snapshot in existing:
-        click.echo(f"[prepare-win] Snapshot '{snapshot}' already exists.")
-        if recreate_snapshot:
-            do_recreate = True
-        else:
-            sys.stdout.write(f"[prepare-win] Delete and recreate '{snapshot}'? [y/N] ")
-            sys.stdout.flush()
-            raw = sys.stdin.readline()
-            do_recreate = raw.strip().lower() in ("y", "yes")
-        if not do_recreate:
-            click.echo("[prepare-win] Keeping existing snapshot. Provisioning complete.")
-            return
-        click.echo(f"[prepare-win] Deleting snapshot '{snapshot}' ...")
+    if snapshot in backend.list_snapshots(handle):
+        click.echo(f"[prepare-win] Deleting existing snapshot '{snapshot}' ...")
         subprocess.run(
             [vmrun_exe, "-T", "ws", "deleteSnapshot", str(vmx_path), snapshot],
             check=True,