fix(push-host-keys): remove /dev/tty probe, plain read is sufficient

/dev/tty exists as a device node even without a controlling terminal,
so -r/-w tests pass but opening it fails. Plain 'read -r -s' from stdin
is enough: works interactively from a real terminal, and from a non-tty
context the caller should set SUDO_PASS in the environment instead.

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

scripts/secrets/push-host-keys.sh

@@ -66,15 +66,8 @@ prompt_sudo_password() {
     sudo_password="$SUDO_PASS"
     return
   fi
-  # Prefer /dev/tty so the prompt works even when stdout/stdin are redirected;
-  # fall back to plain stdin for environments where /dev/tty isn't available.
-  if [[ -r /dev/tty && -w /dev/tty ]]; then
-    read -r -s -p "sudo password for ${SSH_USER} on remote hosts: " sudo_password < /dev/tty
-    echo >&2
-  else
-    read -r -s -p "sudo password for ${SSH_USER} on remote hosts: " sudo_password
-    echo >&2
-  fi
+  read -r -s -p "sudo password for ${SSH_USER} on remote hosts: " sudo_password
+  echo >&2
 }
 
 locally_managed_hosts() {