external: add cargo config; home: set up direnv

.github/workflows/checks.yml

···
       - name: commit message
         uses: adamperkowski/commits@main
         with:
-          scopes: base,home,config,scripts,zsh,systems,docs,ci,chore
+          scopes: base,home,external,zsh,systems,docs,ci,chore

external/cargo.toml

···
+[build]
+target-dir = "/tmp/cargo"

home/adam.nix

···
   age.identityPaths = [ "${config.home.homeDirectory}/.ssh/id_ed25519" ];
 
   imports = [
-    ./modules/scripts.nix
+    ./modules/external.nix
     ./modules/xdg.nix
     ./modules/age.nix
     ./modules/theme.nix

home/modules/external.nix

···
+let
+  configs = ../../external/config;
+  scripts = ../../external/scripts;
+  cargoConfig = ../../external/cargo.toml;
+in
+{
+  home.file = builtins.listToAttrs (
+    map (name: {
+      name = ".local/bin/${builtins.replaceStrings [ ".sh" ] [ "" ] name}";
+      value = {
+        source = scripts + "/${name}";
+        executable = true;
+      };
+    }) (builtins.attrNames (builtins.readDir scripts))
+    ++ [
+      {
+        name = ".cargo/config.toml";
+        value = {
+          source = cargoConfig;
+        };
+      }
+    ]
+  );
+
+  xdg.configFile = builtins.mapAttrs (name: _: {
+    source = configs + "/${name}";
+    recursive = true;
+  }) (builtins.readDir configs);
+}

home/modules/programs/default.nix

···
     ./git.nix
     ./zsh.nix
     ./iamb.nix
+    ./direnv.nix
     ./zoxide.nix
     ./neovim.nix
     ./jellyfin-rpc.nix

home/modules/programs/direnv.nix

···
+{ pkgs, ... }:
+
+{
+  programs.direnv = {
+    enable = true;
+    silent = true;
+    enableZshIntegration = true;
+
+    nix-direnv = {
+      enable = true;
+      package = pkgs.nix-direnv.override { nix = pkgs.lixPackageSets.stable.lix; };
+    };
+
+    stdlib = ''
+      : ''${XDG_CACHE_HOME:=$HOME/.cache}
+      declare -A direnv_layout_dirs
+
+      direnv_layout_dir() {
+        echo "''${direnv_layout_dirs[$PWD]:=$(
+          echo -n "$XDG_CACHE_HOME"/direnv/layouts/
+          echo -n "$PWD" | sha1sum | cut -d ' ' -f 1
+        )}"
+      }
+    '';
+  };
+}

home/modules/programs/zsh.nix

···
     shellAliases = {
       cp = "cp -i";
       nv = "nvim";
+      car = "cat";
       shred = "shred -uvz";
 
-      car = "cat";
+      mkdirenv = "echo -e 'if has nix;then\\n  use flake\\nfi' >> .envrc && direnv allow";
 
       nix-build = "nom build";
       nix-shell = "nom shell";

home/modules/scripts.nix

···
-let
-  scripts = ../../external/scripts;
-in
-{
-  home.file = builtins.listToAttrs (
-    map (name: {
-      name = ".local/bin/${builtins.replaceStrings [ ".sh" ] [ "" ] name}";
-      value = {
-        source = scripts + "/${name}";
-        executable = true;
-      };
-    }) (builtins.attrNames (builtins.readDir scripts))
-  );
-}

home/modules/xdg.nix

···
 { pkgs, ... }:
 
-let
-  configs = ../../external/config;
-in
 {
   xdg = {
     mimeApps.enable = true;
-
-    configFile = builtins.mapAttrs (name: _: {
-      source = configs + "/${name}";
-      recursive = true;
-    }) (builtins.readDir configs);
 
     portal = {
       enable = true;