add niri and update nvim config

.config/niri/dms/alttab.kdl

@@ -0,0 +1,10 @@
+// ! DO NOT EDIT !
+        // ! AUTO-GENERATED BY DMS !
+        // ! CHANGES WILL BE OVERWRITTEN !
+        // ! PLACE YOUR CUSTOM CONFIGURATION ELSEWHERE !
+
+        recent-windows {
+        highlight {
+        corner-radius 12
+        }
+        }