Add templating for dunstrc (monitor from env)

.config/dunst/dunstrc##template

@@ -2,7 +2,7 @@
     ### Display ###
 
     # Which monitor should the notifications be displayed on.
-    monitor = 0
+    monitor = {{ env.DUNST_MONITOR }}
 
     # Display notification on focused monitor.  Possible modes are:
     #   mouse: follow mouse pointer

.config/env.d/98-local-defaults

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+export AUTOSTART_DISPLAY=""
+
+export MONITOR_PRIMARY="primary"
+export MONITOR_SECONDARY="secondary"
+
+export DUNST_MONITOR="0"

.config/env.d/99-local##hostname.portalo

@@ -4,3 +4,5 @@ export AUTOSTART_DISPLAY="Hyprland"
 
 export MONITOR_PRIMARY="DisplayPort-0"
 export MONITOR_SECONDARY="HDMI-A-0"
+
+export DUNST_MONITOR="$MONITOR_SECONDARY"