Fix EVE window detection under Flatpak Steam (bwrap PID namespace)

[arnoldblake]

pid_is_eve_client() rejected every EVE window when Steam runs as a Flatpak, since Proton is sandboxed in its own PID namespace and the window's _NET_WM_PID has no corresponding /proc entry on the host. Fall back to scanning /proc for any exefile.exe process when the reported PID doesn't exist, rather than treating that as "not EVE".

[isomerc]

I like this change in spirit, but it would introduce two problems:

• The window's _NET_WM_PID is namespace local and we only fall back when that pid doesn't exist on the host. The problem is that low pids are usually already taken. It probably worked when you tested it because your pid happened to land on a free slot, but that's something that would be highly flaky on other machines.

• When it does fire, it would cause a regression, matching anything called EVE - [wahtever] which is the browser tab match problem this module was written to fix.

[arnoldblake]

Let me do some additional testing I've moved on from Pop and am running Ubuntu now and I think this is no longer an issue for me.