There is no way to say for sure, but my guess (as well as others) is that production for the Walther PPK stopped in late 1944. I can't say for sure that there were NO PPK's made in 45, but I can say there is no evidence of full production.
Ron Clarin has documented what the GI's found in the factory when they took over in 1945. You will see photos with racks of PP's and crates of P.38's, but NOT a bunch of unfinished PPK's. Random frames and slides, yes. Spare parts? Yes. Enough to put together a few unnumbered PPK? I believe, yes. And I have seen such guns that I would guess were put together from leftover parts. But not like the thousands of Post war PP's and P38's that you can find. GI mismatch PP's and P38's are fairly common. But where are the GI mismatch PPK's?
If you go to the last known serial numbers of a PP or AC45 you will find that they have NO proofs and they are mismatched guns. But if you go to the last 100 known PPK's, you will see that they all have all 3 p