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

docs/file-layout.md

@@ -106,6 +106,7 @@ default/**                     ──►  omarchy-settings    /usr/share/omarchy
   ├─ applications/mimeapps.list                         /usr/share/applications/mimeapps.list
   ├─ systemd/user/*.{service,path}                      /usr/lib/systemd/user/
   ├─ systemd/system-sleep/unmount-fuse                  /usr/lib/systemd/system-sleep/
+  ├─ systemd/zram-generator.conf.d/90-omarchy.conf      /usr/lib/systemd/zram-generator.conf.d/
   ├─ fonts/omarchy/omarchy.ttf                          /usr/share/fonts/omarchy/
   ├─ sddm/omarchy/                                      /usr/share/sddm/themes/omarchy/
   ├─ sddm/hyprland.lua                                  /usr/share/sddm/hyprland.lua
@@ -290,6 +291,7 @@ return to the packaged default.
 | Runtime tweak that needs `$HOME` or live system state | extend `omarchy-finalize-user`, or add a per-user leaf under `install/user/` and wire into `install/user/all.sh` |
 | One-time root-side setup step | `install/config/*.sh` or `install/hardware/*.sh`, wire into `install/config/all.sh` or `install/hardware/all.sh` |
 | One-time fix for existing installs | `migrations/<unix-timestamp>.sh` |
+| Package-owned path something else may already write | Prefer a path nothing else writes, such as a vendor drop-in under `/usr/lib`. Otherwise the `--overwrite` entry in `bin/omarchy-update-system-pkgs` has to ship a release before the file |
 | User-facing `omarchy-*` command | `bin/omarchy-<group>-<verb>` — see `GROUP_DESCRIPTIONS` in `bin/omarchy` |
 | New stock theme | `themes/<name>/` (+ matching templates under `default/themed/` if they need theme colors) |
 | User-installed theme | `~/.config/omarchy/themes/<name>/` |