Disc brake rotor scraping against mounting bracket (My question is related to Rear disc brake rotor rubbing against caliper frame mount? but I hope to provide some more context &amp; photos.)

I have a Rocky Mountain Edge mountain bike (possibly 2011 or 2012) that has factory-installed Shimano hydraulic disc brakes. I was replacing a flat front tire today and had trouble getting the rotor aligned inside the caliper. When I took a closer look, I was surprised to see that the disc has been rubbing against the front fork mounting bracket along at least half of its radius.

This photo shows the wear to the mounting bracket and the caliper support (there is corresponding wear on the rotor):



(n.b. the bike was upside down when this photo was taken: dropouts are on the left, and the rear of the bike is toward the right.)

To me, it seems like there's an issue with where the wheel sits relative to the fork (i.e. that it's a few millimetres too close to the caliper side). The rotor seems to be permanently affixed to the wheel (no screws), and it doesn't appear to have moved relative to the hub. Looking at the quick-release skewer, it seems like all the parts are there, but it still doesn't sit properly.

How can I solve this problem? Is there a spacer I can add to the quick-release skewer so the rotor sits the proper distance from the fork? Is there a specific offset for this type of brake caliper? 

Is it likely to be caused by a damaged wheel? (The rim is quite out of shape, so I could use this as an opportunity to replace the whole wheel.)

EDIT: some more photos:
A few things can cause this:


In theory it could be a problem with the alignment of the mounting posts on the fork. This isn't likely for a few reasons. One is that the problem would have been pretty egregious if the bike was doing it from day one, i.e. the wheel wouldn't have turned and someone would have noticed. Another is that suspension forks rarely have such problems because the brake mount is usually part of the same casting as the dropout, and in that case you're not going to have random one-off problems with bad positioning of the mounts due to fixturing errors at the factory, which does sometimes happen with frames.
A sufficiently out of true rotor could do this.
If the wheel were installed out of alignment in the fork and ridden it could cause this.
If the hub parts were put together wrong, after service for example, it could do this by creating an incorrect distance between the rotor surface and the left locknut service. Between the plane of the back shoulder area of the centerlock mount and the plane of the left dropout should be about 19.5mm. If this happened, it would also throw off the wheel dish unless that was corrected afterward to compensate.