Revert "make host key check an enum instead of an literal type"

This reverts commit 543c518ed0.

pkgs/clan-cli/clan_cli/machines/install.py

@@ -13,7 +13,6 @@ from clan_cli.completions import (
     complete_machines,
     complete_target_host,
 )
-from clan_cli.host_key_check import add_host_key_check_arg
 from clan_cli.machines.hardware import HardwareConfig
 from clan_cli.ssh.deploy_info import DeployInfo, find_reachable_host, ssh_command_parse
 
@@ -98,7 +97,12 @@ def register_install_parser(parser: argparse.ArgumentParser) -> None:
         help="do not reboot after installation (deprecated)",
         default=False,
     )
-    add_host_key_check_arg(parser)
+    parser.add_argument(
+        "--host-key-check",
+        choices=["strict", "ask", "tofu", "none"],
+        default="ask",
+        help="Host key (.ssh/known_hosts) check mode.",
+    )
     parser.add_argument(
         "--build-on",
         choices=[x.value for x in BuildOn],