I don’t believe there is one.  I think the closest we’ve seen to an actual type of binding is {gho paq} “[ring] binder, notebook” (qepHom 2015) which is clearly different.  There is also this discussion Lieven had with Okrand  at qepHom 2015:

(Lieven, 11/05/2015):  I asked Okrand about this [i.e. envelope], and he first said "Why can't a thing have two words?"  He later went into detail, saying that a {vaH} [i.e. “holster, sheath“] can be used for any kind of cover you use to put things in, for instance also a CD sleeve.  The {vaH} is usually a finished piece of material.  The word {qatwI'} is a more literal translation of the meaning "envelope".  Sometimes you can look at an envelope and see how it's made: it's a piece of paper wrapping around something.  Next Okrand said that if there were a Klingon-Klingon dictionary, {nav qatwI'} would be a good description for a {nav vaH}.

{nav qatwI’} also works for a paperback cover or dust jacket.  This suggests *{'echlet  qatwI’} for a (card)board cover,  *{(qo’rIn) DIr qatwI’} for a leather cover, etc. 

In addition to {qat} “wrap, encase”, {Qan} “protect” is another option.  We know of:

    DIr QanwI' taS              suntan lotion (TNK)
    mIn QanwI'                    eyeglasses (TNK)
    tal QanwI'                      cannon guard [i.e. armor-plated] (KBoP)

{QanwI’} feels more substantial than a {qatwI’}, rather like a slipcase or shell box (both of which I deal with on a regular basis as a rare book cataloger at the University of Chicago Library).

--
Voragh

________________________________________________________________

From: tlhIngan-Hol On Behalf Of De'vID

On Thu, 21 Oct 2021 at 16:23, SuStel <sustel@trimboli.name> wrote:

They probably just slapped together a quick mock-up, and whoever did it
flipped the image for some reason (fitting on the page?) didn't notice
or didn't care that this made the image backwards.

ghaytan bIlugh. paq mIllogh po'oHDaq mu'meyvam tu'lu': "Final Cover to be Revealed".

(chay' "cover (of a book)" jatlhlu'?)