Fixes #19872: Display form validation errors for script execution

When script form validation fails (e.g., required fields excluded from
fieldsets), display error messages via Django's message framework instead
of failing silently. Error format: "field: error1, error2; field2: error".

netbox/extras/views.py

@@ -1485,6 +1485,11 @@ class ScriptView(BaseScriptView):
             )
 
             return redirect('extras:script_result', job_pk=job.pk)
+        else:
+            messages.error(
+                request,
+                '; '.join(f"{field}: {', '.join(errors)}" for field, errors in form.errors.items())
+            )
 
         return render(request, 'extras/script.html', {
             'object': script,