omarchy-first-run: run setup-user first; fix gdk-scale.sh for lua config

Two bugs caused fresh users to land without branding files / AI skill
symlinks / nautilus extensions / xdg dirs / etc.:

1. install/first-run/gdk-scale.sh sed-edited ~/.config/hypr/monitors.conf,
   but the lua-based config flow uses ~/.config/hypr/monitors.lua. sed -i
   on the missing .conf returned non-zero, set -e fired, omarchy-first-run
   aborted mid-block AFTER deleting ~/.local/state/omarchy/first-run.mode.
   omarchy-setup-user (called at the bottom of the script, outside the
   if-block) never ran, so setup-user.done never got written and the
   per-user defaults (~/.config/omarchy/branding/*, ~/.agents/skills/omarchy,
   xdg dirs, etc.) never got created.

   Replace the .conf sed with a call to omarchy-hyprland-monitor-scaling
   which already knows how to persist into monitors.lua.

2. Move 'omarchy-setup-user || true' to the TOP of omarchy-first-run, before
   the privileged first-run block. setup-user is idempotent and gated on
   its own marker, so running it first is safe and means a failure in any
   of the privileged steps can't prevent user setup from completing.

bin/omarchy-first-run

@@ -5,6 +5,12 @@
 
 set -e
 
+# Run user-level setup FIRST so its outcome (→ branding files, AI skill
+# symlinks, xdg dirs, etc.) isn't held hostage to whether one of the
+# privileged first-run steps below aborts under set -e. omarchy-setup-user
+# is idempotent and gated on its own marker.
+omarchy-setup-user || true
+
 FIRST_RUN_MODE=~/.local/state/omarchy/first-run.mode
 
 if [[ -f $FIRST_RUN_MODE ]]; then
@@ -23,7 +29,3 @@ if [[ -f $FIRST_RUN_MODE ]]; then
   bash "$OMARCHY_PATH/install/first-run/welcome.sh"
   bash "$OMARCHY_PATH/install/first-run/wifi.sh"
 fi
-
-# omarchy-setup-user is idempotent (gated on its own marker), so this is
-# safe to call on every invocation — it'll no-op once user setup is done.
-omarchy-setup-user || true