Ship zram tuning as a vendor drop-in

pacman checks file conflicts during transaction prepare, so the --overwrite
entry added alongside /etc/systemd/zram-generator.conf never got to run: the
copy of omarchy-update-system-pkgs driving the upgrade is the one already on
disk. Every machine carrying archinstall's copy aborted the transaction.

zram-generator.conf(5) reserves /etc for the local admin and has vendors ship
snippets under /usr/lib/systemd/zram-generator.conf.d/, where drop-ins outrank
the main config file. Nothing collides, and the tuning wins whether or not
archinstall's file is still around.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LjeyQZsNBxqyYy9z8KaKm7

bin/omarchy-upgrade-to-quattro

@@ -1087,7 +1087,6 @@ run_final_system_package_upgrade() {
     --overwrite '/etc/systemd/system/plocate-updatedb.service.d/ac-only.conf' \
     --overwrite '/etc/systemd/system.conf.d/20-omarchy-nofile.conf' \
     --overwrite '/etc/systemd/user.conf.d/20-omarchy-nofile.conf' \
-    --overwrite '/etc/systemd/zram-generator.conf' \
     --overwrite '/usr/lib/systemd/system-sleep/unmount-fuse' \
     --overwrite '/usr/share/plymouth/themes/omarchy/*' \
     --overwrite '/usr/share/sddm/hyprland.lua' \