add niri and update nvim config

.config/niri/dms/layout.kdl

@@ -0,0 +1,22 @@
+// ! DO NOT EDIT !
+        // ! AUTO-GENERATED BY DMS !
+        // ! CHANGES WILL BE OVERWRITTEN !
+        // ! PLACE YOUR CUSTOM CONFIGURATION ELSEWHERE !
+
+        layout {
+        gaps 4
+
+        border {
+        width 2
+        }
+
+        focus-ring {
+        width 2
+        }
+        }
+        window-rule {
+        geometry-corner-radius 12
+        clip-to-geometry true
+        tiled-state true
+        draw-border-with-background false
+        }