chore: ignore Windows NUL device artifact in .gitignore

The name `nul` is a Windows reserved device that appears as an untracked
entry in git status when shells redirect to it. Adding it to .gitignore
suppresses the noise without touching anything committed.

Signed-off-by: fOuttaMyPaint <tmhospitalitystrategies@gmail.com>
Signed-off-by: fOuttaMyPaint <154358121+TMHSDigital@users.noreply.github.com>

Author: TMHSDigital

.gitignore

@@ -45,3 +45,6 @@ Thumbs.db
 output/
 _scaffold*/
 /tmp/
+
+# Windows NULL device - appears as untracked on Windows when shells redirect to nul
+nul