fix problems rebuilding, make niri and noctalia more HM friendly

added `inputs` to `extraSpecialArgs`, giving homeModules access to helper functions
cleaned up the logic for the stylix file, removing the final `sharedModules` in the process in favour of `home-manager.users.grey`

dotfiles/kitagawa/niri.kdl

@@ -27,7 +27,7 @@ input {
 }
 screenshot-path "~/Pictures/Screenshots/Screenshot from %Y-%m-%d %H-%M-%S.png"
 prefer-no-csd
-overview { zoom 0.666; }
+overview { zoom 0.5; }
 layout {
     gaps 12
     struts {
@@ -158,4 +158,8 @@ animations {
     window-resize {
         spring damping-ratio=0.8 stiffness=650 epsilon=0.0001
     }
+}
+layer-rule {
+  match namespace="^noctalia-backdrop"
+  place-within-backdrop true
 }