refactor: move impermanence config to application definition where possible

users/myuser/dev/default.nix

@@ -0,0 +1,17 @@
+{pkgs, ...}: {
+  imports = [
+    ./direnv.nix
+    ./gdb.nix
+  ];
+
+  home = {
+    extraOutputsToInstall = ["doc" "devdoc"];
+    packages = with pkgs; [
+      git-lfs
+      d2
+      cloc
+    ];
+  };
+
+  programs.nix-index.enable = true;
+}

users/myuser/dev/direnv.nix

@@ -0,0 +1,22 @@
+{
+  programs.direnv = {
+    enable = true;
+    nix-direnv.enable = true;
+
+    # Store layout configs in an XDG directory and not in a .direnv local directory
+    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" | shasum | cut -d ' ' -f 1
+          )}"
+      }
+    '';
+  };
+
+  home.persistence."/state".directories = [
+    ".local/share/direnv"
+  ];
+}

users/myuser/dev/gdb.nix

@@ -0,0 +1,8 @@
+{
+  home.file.gdbinit = {
+    target = ".gdbinit";
+    text = ''
+      set auto-load safe-path /
+    '';
+  };
+}