refactor: more sane profile structure

profiles/home/common/nix-index.nix

@@ -0,0 +1,21 @@
+{ self, pkgs, ... }:
+{
+  programs.nix-index =
+    let
+      commandNotFound = pkgs.runCommandLocal "command-not-found.sh" { } ''
+        mkdir -p $out/etc/profile.d
+        substitute ${self + /scripts/command-not-found.sh}        \
+          $out/etc/profile.d/command-not-found.sh                 \
+          --replace @nix-locate@ ${pkgs.nix-index}/bin/nix-locate \
+          --replace @tput@ ${pkgs.ncurses}/bin/tput
+      '';
+    in
+
+    {
+      enable = true;
+      package = pkgs.symlinkJoin {
+        name = "nix-index";
+        paths = [ commandNotFound ];
+      };
+    };
+}