chore: Use $XDG_CONFIG_HOME in lfrc (#554)

.config/lf/lfrc

@@ -2,7 +2,6 @@
 
 # Basic vars
 set shell bash
-set previewer ~/.config/lf/scope
 set shellopts '-eu'
 set ifs "\n"
 set scrolloff 10
@@ -10,6 +9,9 @@ set color256
 set icons
 set period 1
 
+# Vars that depend on environmental variables
+$lf -remote "send $id set previewer ${XDG_CONFIG_HOME:-$HOME/.config}/lf/scope"
+
 # cmds/functions
 cmd open ${{
     case $(file --mime-type $f -b) in