fix(template): use sys.stdin.readline() for snapshot confirm prompt

input() with a prompt string on some terminals (zsh + Linux Mint) echoes
^M and the prompt doesn't flush before reading, causing the prompt to
appear stuck or not accept input.

Replace with explicit sys.stdout.write()+flush() + sys.stdin.readline()
which guarantees the prompt is flushed before blocking on stdin, and
readline() + .strip() handles both \n and \r\n line endings correctly.

Tests updated to use CliRunner(input=) which populates sys.stdin inside
the runner context (monkeypatching sys.stdin.readline directly is ignored
by CliRunner which replaces sys.stdin entirely).

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

src/ci_orchestrator/commands/template.py

@@ -60,6 +60,7 @@ import json
 import shutil
 import socket
 import subprocess
+import sys
 import threading
 import time
 from datetime import UTC, datetime
@@ -671,8 +672,10 @@ Register-ScheduledTask -TaskName 'CI-StaticIp' `
         if recreate_snapshot:
             do_recreate = True
         else:
-            raw = input(f"[prepare-win] Delete and recreate '{snapshot}'? [y/N] ")
-            do_recreate = raw.strip().rstrip("\r").lower() in ("y", "yes")
+            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