niri/waybar: some fixes, new module

Signed-off-by: unexplrd <unexplrd@linerds.us>

modules/home/desktop/niri/niri.nix

@@ -215,6 +215,12 @@ in {
             off
         }
     }
+    layer-rule {
+      match namespace="waybar"
+      match at-startup=true
+
+      opacity 0.99 // fixes the black fill
+    }
 
     window-rule {
       match title="Картинка в картинці"
@@ -250,6 +256,7 @@ in {
         block-out-from "screencast"
     }
 
+
     binds {
       Mod+Shift+Slash  { show-hotkey-overlay; }