feat: Niri additions

- Switch to unstable branch.
- Run xwayland-sattelite as a serivce.
- Initialise terminal windows at smaller widths.
- Style & bind tabs.
- Block out private windows.
- Binds for dynamic casting.

hosts/sydpc/configuration.nix

@@ -73,7 +73,7 @@
     videoDrivers = [ "nvidia" ];
     xkb = {
       layout = "us";
-      options = "ctrl:swapcaps";
+      options = "ctrl:swapcaps,compose:menu";
     };
   };