Manage the SSH terminfo cache for automatic remote host setup.

When SSH integration is enabled with `shell-integration-features = ssh-terminfo`,
Ghostty automatically installs its terminfo on remote hosts. This command
manages the cache of successful installations to avoid redundant uploads.

The cache stores hostnames (or user@hostname combinations) along with timestamps.
Entries older than the expiration period are automatically removed during cache
operations. By default, entries never expire.

Only one of `--clear`, `--add`, `--remove`, or `--host` can be specified.
If multiple are specified, one of the actions will be executed but
it isn't guaranteed which one. This is entirely unsafe so you should split
multiple actions into separate commands.

Examples:
  ghostty +ssh-cache                          # List all cached hosts
  ghostty +ssh-cache --host=example.com       # Check if host is cached
  ghostty +ssh-cache --add=example.com        # Manually add host to cache
  ghostty +ssh-cache --add=user@example.com   # Add user@host combination
  ghostty +ssh-cache --remove=example.com     # Remove host from cache
  ghostty +ssh-cache --clear                  # Clear entire cache
  ghostty +ssh-cache --expire-days=30         # Set custom expiration period