Switch dev-link mechanism from shadow-dir to /etc/omarchy.conf

omarchy-dev-link (lands in a follow-up) writes OMARCHY_PATH=<checkout>
to /etc/omarchy.conf. Three boot/session entry points now source it
before falling back to /usr/share/omarchy:

- /etc/profile.d/omarchy.sh   (login shells, SSH)
- config/uwsm/env             (Hyprland session via UWSM)
- default/bash/envs           (non-login interactive bash; duplicated for
                              SSH and similar)

All three use 'export OMARCHY_PATH="${OMARCHY_PATH:-/usr/share/omarchy}"'
so /etc/omarchy.conf wins over the default, and install.sh's script-mode
export wins over /etc/omarchy.conf (because both use the :- guard).

Hyprland updates session env on the fly via hyprctl setenv +
systemctl --user import-environment, so omarchy-dev-link can re-trigger
those to make live sessions pick up the new path without restart.

config/uwsm/env

@@ -1,8 +1,11 @@
 # Changes require a restart to take effect.
 
-# Ensure Omarchy bins are in the path. /etc/profile.d/omarchy.sh defaults
-# OMARCHY_PATH to /usr/share/omarchy; honor whatever's already set (so
-# install.sh's script-mode override wins).
+# Source /etc/omarchy.conf so omarchy-dev-link (which writes
+# OMARCHY_PATH=<checkout> there) wins over the default. install.sh's
+# script-mode export still wins because the file uses the same :- guard.
+# UWSM doesn't source /etc/profile.d/, so this duplicates that logic for the
+# Hyprland session.
+[ -f /etc/omarchy.conf ] && . /etc/omarchy.conf
 export OMARCHY_PATH="${OMARCHY_PATH:-/usr/share/omarchy}"
 export PATH="$OMARCHY_PATH/bin:$PATH:$HOME/.local/bin"