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.

etc/profile.d/omarchy.sh

@@ -1,24 +1,14 @@
-# Default OMARCHY_PATH for non-install shells.
-#
-# - install.sh sets OMARCHY_PATH to $HOME/.local/share/omarchy during the
-#   script-install (boot.sh) flow; that wins because of the :- guards.
-# - omarchy-dev-link manages /usr/share/omarchy-dev as a symlink to a local
-#   checkout. When present, it shadows the package install for everything
-#   that resolves via $OMARCHY_PATH (bin/, default/, shell/, themes/).
-# - Otherwise: the package install at /usr/share/omarchy.
-if [ -z "${OMARCHY_PATH:-}" ]; then
-  if [ -d /usr/share/omarchy-dev ]; then
-    export OMARCHY_PATH=/usr/share/omarchy-dev
-  else
-    export OMARCHY_PATH=/usr/share/omarchy
-  fi
-fi
+# Source /etc/omarchy.conf first so dev-link or other system overrides can
+# pre-set OMARCHY_PATH (and anything else) before the defaults run.
+# install.sh's script-mode export still wins because /etc/omarchy.conf uses
+# the same :- guard.
+[ -f /etc/omarchy.conf ] && . /etc/omarchy.conf
+export OMARCHY_PATH="${OMARCHY_PATH:-/usr/share/omarchy}"
 
 # Prepend $OMARCHY_PATH/bin if it exists. In normal package mode this is a
 # no-op: bins ship to /usr/bin (already on PATH), and /usr/share/omarchy/bin
-# doesn't exist. The case that matters is omarchy-dev-link, which exposes the
-# checkout's bin/ at /usr/share/omarchy-dev/bin so it can override the
-# /usr/bin copies the package installed.
+# doesn't exist. When omarchy-dev-link is active OMARCHY_PATH points at a
+# local checkout, whose bin/ then overrides the /usr/bin copies.
 case ":$PATH:" in
   *":$OMARCHY_PATH/bin:"*) ;;
   *) [ -d "$OMARCHY_PATH/bin" ] && export PATH="$OMARCHY_PATH/bin:$PATH" ;;