make host key check an enum instead of an literal type

this is more typesafe at runtime.

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

@@ -12,6 +12,7 @@ from clan_lib.machines.suggestions import validate_machine_names
 from clan_lib.ssh.remote import Remote
 
 from clan_cli.completions import add_dynamic_completer, complete_machines
+from clan_cli.host_key_check import add_host_key_check_arg
 
 from .types import machine_name_type
 
@@ -54,12 +55,7 @@ def register_update_hardware_config(parser: argparse.ArgumentParser) -> None:
         nargs="?",
         help="ssh address to install to in the form of user@host:2222",
     )
-    parser.add_argument(
-        "--host-key-check",
-        choices=["strict", "ask", "tofu", "none"],
-        default="ask",
-        help="Host key (.ssh/known_hosts) check mode.",
-    )
+    add_host_key_check_arg(parser)
     parser.add_argument(
         "--password",
         help="Pre-provided password the cli will prompt otherwise if needed.",

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

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

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

@@ -16,6 +16,7 @@ from clan_cli.completions import (
     complete_machines,
     complete_tags,
 )
+from clan_cli.host_key_check import add_host_key_check_arg
 
 log = logging.getLogger(__name__)
 
@@ -163,12 +164,7 @@ def register_update_parser(parser: argparse.ArgumentParser) -> None:
     )
     add_dynamic_completer(tag_parser, complete_tags)
 
-    parser.add_argument(
-        "--host-key-check",
-        choices=["strict", "ask", "tofu", "none"],
-        default="ask",
-        help="Host key (.ssh/known_hosts) check mode.",
-    )
+    add_host_key_check_arg(parser)
     parser.add_argument(
         "--target-host",
         type=str,