[backport] Fix Dart Sass failing in enterprise Windows with Group Policy restrictions (#14369)

* Fall back to direct sass.bat execution when safeWindowsExec fails

Enterprise Windows environments with Group Policy / AppLocker rules
that block .bat execution from %TEMP% cause the safeWindowsExec temp
wrapper to fail, breaking dart-sass invocation (regression from #14002).

Try safeWindowsExec first (handles spaces in paths), then fall back to
direct execProcess call (v1.8 behavior) when it fails.

Fixes #14367

* Add changelog entry for #14367

Author: cderv

news/changelog-1.9.md

@@ -3,6 +3,7 @@
 ## In this release
 
 - ([#14304](https://github.com/quarto-dev/quarto-cli/issues/14304)): Fix `quarto install tinytex` silently ignoring extraction failures. When archive extraction fails (e.g., `.tar.xz` on a system without `xz-utils`), the installer now reports a clear error instead of proceeding and failing with a confusing `NotFound` message.
+- ([#14367](https://github.com/quarto-dev/quarto-cli/issues/14367)): Fix Dart Sass invocation failing on enterprise Windows systems where Group Policy blocks `.bat` execution from `%TEMP%`. When the `safeWindowsExec` temp wrapper is blocked, Quarto now falls back to calling `sass.bat` directly.
 
 ## In previous releases
 

src/core/dart-sass.ts

@@ -125,7 +125,22 @@ export async function dartCommand(
         });
       },
     );
-    return processResult(result);
+    if (result.success) {
+      return processResult(result);
+    }
+
+    // safeWindowsExec failed — fall back to direct execution (v1.8 behavior).
+    // Enterprise environments may block .bat execution from %TEMP% via
+    // Group Policy / AppLocker, causing the temp wrapper to fail.
+    // See https://github.com/quarto-dev/quarto-cli/issues/14367
+    debug("[DART] safeWindowsExec failed, falling back to direct execution");
+    const directResult = await execProcess({
+      cmd: sass,
+      args,
+      stdout: "piped",
+      stderr: "piped",
+    });
+    return processResult(directResult);
   }
 
   // Non-Windows: direct execution