Timeshift and tmux

Added in support for timeshift and added in cron services with
correct entry so that timeshift will take snapshots properly
on a schedule. Added in and configured tmux support. Was thinking
of using zellij but tmux just integrates so much nicer to nix.

base-config.nix

@@ -142,6 +142,14 @@
   # Now add the zsh shell to /etc/shells so others can set their shell
   environment.shells = with pkgs; [ zsh ];
 
+  # Enable tmux support and configure it to our usage
+  programs.tmux = {
+    enable = true;
+    keyMode = "vi";
+    shortcut = "s";
+    clock24 = true;
+  };
+
   # Some programs need SUID wrappers, can be configured further or are
   # started in user sessions.
   # programs.mtr.enable = true;
@@ -152,6 +160,12 @@
 
   # List services that you want to enable:
 
+  # Enable Vixie cron service
+  services.cron.enable = true;
+  services.cron.systemCronJobs = [
+    "0 * * * * root timeshift --check --scripted"
+  ];
+
   # Enable the OpenSSH daemon.
   # services.openssh.enable = true;