Cleanup Automation

Added in configuration options to automatically optimize the
nix-store and automatically garbage collect stale references
in the store after 2 weeks.

configs/desktop.nix

@@ -104,6 +104,17 @@
     '';
   };
 
+  # Enable automatic optimization of the nix store
+  nix.settings.auto-optimise-store = true;
+
+  # Enable automatic garbage collection on anything
+  # stale and older than 2 weeks
+  nix.gc = {
+    automatic = true;
+    dates = "weekly";
+    options = "--delete-older-than 14d";
+  };
+
   # Setup our ZSH shell.
   # First let's absolutely make sure the shell is enabled
   programs.zsh.enable = true;