fix: allow running rootless

[djrarky]

When running Nutify rootless, the container user cannot change ownership or permissions for /dev/bus/usb, which can cause the startup permission-fix loop to block service startup. This adds a SKIP_PERMCHECK environment variable to bypass the USB permission update step when the host already manages device permissions (e.g., via udev/systemd), allowing Nutify to start without trying to chown/chmod

[jumbi77]

Cool! I also want to use nutify docker rootless because my driver is only snmp-ups, so no USB or direct hardware access is not needed.

Just a few thoughts:

• Maybe name the new environment variable (SKIP_PERMCHECK) more generic like SKIP_USB_CHECK or NO_USB_SUPPORT ... ?
• Maybe also place the environment variable in the example docker compose? (...of course default is SKIP_PERMCHECK =false)

[djrarky]

I used SKIP_PERMCHECK as I'm using it with USB. I just don't want nut to own the device.

I did mess up with the env variable in the git commit - I put it into the wrong branch, but if it's merged, it'll be added with #114.