What is this faint black shadow line on top of my photos/negatives?

[bud.petal]

Maybe a dumb question, but are you sure the defect is in the negative? Or could it be in the scan or print process, not in the negative?

I also thought the problem was in the development or scanning process, but the issue is very obvious on the negatives too. I'm hoping the problem is with how the film sits inside the camera.

 

[Sarcophilus Harrisii]

If you put another roll of film through it before getting it looked at, run a series of images as above with plenty of clear sky. Set shutter times from 1/1000 to 1/30, adjusting aperture to maintain identical exposure. If the impact on the edge exposure varies with shutter speed and decreases with longer times, (1/1000 would be most affected) it's definitely curtain bounce. If the banding issue is unaffected by exposure time it's probably an obstruction/film alignment issue.
Cheers
Brett