Change file location of cachyos-bugreport.sh

Hey,

if I run `cachyos-bugreport.sh` the log gets saved in the current directory.
I think we should move the log file to `/var/log` to get a centralized/fixed place.

Yes the files are small, but if I do it in many different locations, I'll get the files in every directory which feels a bit inconsistent.

Can do a PR, if oppinions are the same

Start by locating cachyos-bugreport.sh and inspect how it chooses the log output path. Confirm the current-directory behavior, then assess the proposed /var/log location and its implications for running the script. Done means the report is consistently saved in the agreed centralized location.

Written by the indexing model from the issue text.