fix(template): restore tty state before snapshot prompt to fix ^M issue

pypsrp alters terminal tty settings during WinRM sessions. This causes
readline() at the snapshot prompt to receive \r (not \n) on Enter,
printing ^M repeatedly without ever unblocking.

Fix: save termios attributes at command start (before any WinRM work,
terminal is clean) and restore them with tcsetattr(TCSADRAIN) before
the interactive snapshot prompt. Gracefully skips save/restore when
stdin is not a tty (tests, pipes, CI).

Revert the pre-flight snapshot check approach (commit f6f8ffc) — checking
at start was architecturally wrong (snapshot state may change during
provisioning). The prompt stays at the end where it belongs.

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

src/ci_orchestrator/commands/template.py

@@ -432,26 +432,21 @@ def template_prepare_win(
     if not build_password:
         build_password = click.prompt(f"New {build_username} password", hide_input=True)
 
-    # --- Pre-flight snapshot conflict check (terminal still clean here) ---
+    # Save tty state now (terminal clean) so we can restore it before any
-    # Must happen before any WinRM/pypsrp calls, which alter tty state and
+    # interactive prompt at the end — pypsrp alters tty settings during
-    # prevent readline() from receiving \n on Enter.
+    # WinRM sessions, causing readline() to receive \r instead of \n.
+    _tty_fd = sys.stdin.fileno() if sys.stdin.isatty() else -1
+    _saved_tty_attrs: list[object] = []
+    if _tty_fd >= 0:  # pragma: no cover
+        try:
+            import termios
+            _saved_tty_attrs.append(termios.tcgetattr(_tty_fd))
+        except Exception:
+            pass
+
     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} ...")
@@ -680,10 +675,31 @@ Register-ScheduledTask -TaskName 'CI-StaticIp' `
         raise click.ClickException("VM did not power off within 120s.")
     click.echo("[prepare-win] VM powered off.")
 
-    # Create snapshot — conflict already resolved at pre-flight above.
+    # Restore tty state before interactive prompt — pypsrp alters terminal
+    # settings and readline() would receive \r instead of \n on Enter.
+    if _saved_tty_attrs and _tty_fd >= 0:  # pragma: no cover
+        try:
+            import termios
+            termios.tcsetattr(_tty_fd, termios.TCSADRAIN, _saved_tty_attrs[0])  # type: ignore[arg-type]
+        except Exception:
+            pass
+
+    # Create snapshot
     vmrun_exe = backend.vmrun_path
-    if snapshot in backend.list_snapshots(handle):
+    existing = backend.list_snapshots(handle)
-        click.echo(f"[prepare-win] Deleting existing snapshot '{snapshot}' ...")
+    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}' ...")
         subprocess.run(
             [vmrun_exe, "-T", "ws", "deleteSnapshot", str(vmx_path), snapshot],
             check=True,