fix: enable variable expansion in cluster node SSH key heredoc

Changed heredoc delimiter from <<'EOF' to <<EOF to allow bash variable
expansion. Previously $SSH_PUBLIC_KEY and $SSH_RESTRICTED_KEY_ENTRY
were being passed as literal strings instead of their actual values,
so cluster nodes never received the correct SSH keys.

This fixes cluster node ProxyJump setup - now both restricted and
unrestricted keys are properly added to cluster nodes.

internal/api/config_handlers.go

@@ -4058,7 +4058,7 @@ if [ "$TEMPERATURE_ENABLED" = true ] && command -v pvecm >/dev/null 2>&1 && comm
                 if [[ $REMOTE_REPLY =~ ^[Yy]$ ]]; then
                     for NODE in "${OTHER_NODES_LIST[@]}"; do
                         echo "Configuring temperature monitoring on $NODE..."
-                        if ssh -o BatchMode=yes -o StrictHostKeyChecking=no -o ConnectTimeout=5 -o LogLevel=ERROR root@"$NODE" "bash -s" <<'EOF'
+                        if ssh -o BatchMode=yes -o StrictHostKeyChecking=no -o ConnectTimeout=5 -o LogLevel=ERROR root@"$NODE" "bash -s" <<EOF
 set -e
 SSH_PUBLIC_KEY='$SSH_PUBLIC_KEY'
 SSH_RESTRICTED_KEY_ENTRY='$SSH_RESTRICTED_KEY_ENTRY'