Replace command-not-found with nix-index

Add nano syntax highlighting

flake.nix

@@ -82,7 +82,25 @@
                 systemd-boot.enable = true;
                 efi.canTouchEfiVariables = true;
               };
-              programs.${shell}.enable = true;
+              programs = {
+                ${shell}.enable = true;
+                nano = {
+                  enable = true;
+                  syntaxHighlight = true;
+                  nanorc = ''
+                    set nowrap
+                    set tabstospaces
+                    set tabsize 2
+                  '';
+                };
+                command-not-found.enable = false;
+                nix-index = {
+                  enable = true;
+                  enableBashIntegration = true;
+                  enableFishIntegration = true;
+                  enableZshIntegration = true;
+                };
+              };
               nix = {
                 enable = true;
                 settings = {
@@ -90,7 +108,10 @@
                   auto-optimise-store = true;
                 };
                 channel.enable = false;
-                nixPath = [ "nixpkgs=${inputs.nixpkgs}" ];
+                nixPath = [
+                  "nixpkgs=${pkgs.path}"
+                  "/nix/var/nix/profiles/per-user/root/channels"
+                ];
                 registry = {
                   nixpkgs.to = {
                     type = "path";