♻️ [shared] Moved files to base shared directory

shared/base/modules/shell.nix

@@ -0,0 +1,19 @@
+# For Fish dotfiles, see: /home-manager/fish.nix
+{ pkgs, ... }:
+
+{
+  programs = {
+    bash = {
+      # Starts the OS using Bash, then starts fish if it's not running
+      interactiveShellInit = ''
+        if [[ $(${pkgs.procps}/bin/ps --no-header --pid=$PPID --format=comm) != "fish" && -z ''${BASH_EXECUTION_STRING} ]]
+        then
+          shopt -q login_shell && LOGIN_OPTION='--login' || LOGIN_OPTION=""
+          exec ${pkgs.fish}/bin/fish $LOGIN_OPTION
+        fi
+      '';
+    };
+
+    fish.enable = true;
+  };
+}