home: add atuin

I really like the `fzf` history widget, and this is not as good UI-wise.

However I like the fact that this uses a DB:

* It is more reliable when the history file gets messed up [1]
* It allows syncing between different hosts (not sure if I will use it)
* It adds more context to the search
    * The current directory
    * The shell _session_, I can *either* search all sessions or
      restrict to just the current one

I will be looking into whether or not I can hack something together to
get a better UI (by using `fzf` of course).

home/default.nix

@@ -1,6 +1,7 @@
 { ... }:
 {
   imports = [
+    ./atuin
     ./bat
     ./bluetooth
     ./comma