rework: fix all vulnerabilities

package/windows-devshell/default.nix

@@ -1,26 +1,10 @@
-{ pkgs, writeTextFile, lib, linux-devshell-standalone }:
-let
-  psScriptTemplate = builtins.readFile ./windows-devshell.ps1;
-
-  # Get the linux-devshell standalone script content and base64 encode it
-  linuxDevShellBase64 = lib.removeSuffix "\n"
-    (builtins.readFile
-      (pkgs.runCommand "base64-linux-devshell" {}
-        ''
-          ${pkgs.coreutils}/bin/base64 -w 0 ${linux-devshell-standalone} > $out
-        ''));
-
-  # Standalone PowerShell script (single file for Windows)
-  windowsDevShellStandalone = writeTextFile {
-    name = "windows-devshell.ps1";
-    executable = false;
-    text = lib.replaceStrings ["@LINUX_DEVSHELL_BASE64@"] [linuxDevShellBase64] psScriptTemplate;
-    meta = {
-      description = "Standalone windows-devshell PowerShell script (single file)";
-    };
-  };
-
-in
+{ pkgs, linux-devshell-standalone }:
 {
-  windows-devshell-standalone = windowsDevShellStandalone;
+  windows-devshell-standalone = pkgs.runCommand "windows-devshell.ps1" {
+    meta.description = "Standalone windows-devshell PowerShell script (single file)";
+  } ''
+    linux_dev_shell_base64=$(${pkgs.coreutils}/bin/base64 -w 0 ${linux-devshell-standalone})
+    ${pkgs.gnused}/bin/sed "s|@LINUX_DEVSHELL_BASE64@|$linux_dev_shell_base64|g" \
+      ${./windows-devshell.ps1} > "$out"
+  '';
 }