fix: clean up Add Stamp image preview blob URLs (#6779)

Co-authored-by: James Brunton <jbrunton96@gmail.com>

frontend/editor/src/core/components/tools/addStamp/StampSetupSettings.tsx

@@ -19,6 +19,7 @@ import { AddStampParameters } from "@app/components/tools/addStamp/useAddStampPa
 import ButtonSelector from "@app/components/shared/ButtonSelector";
 import styles from "@app/components/tools/addStamp/StampPreview.module.css";
 import { getDefaultFontSizeForAlphabet } from "@app/components/tools/addStamp/StampPreviewUtils";
+import { useFileWithUrl } from "@app/hooks/useFileWithUrl";
 import { Z_INDEX_AUTOMATE_DROPDOWN } from "@app/styles/zIndex";
 
 const STAMP_TEMPLATES = [
@@ -209,6 +210,9 @@ const StampSetupSettings = ({
   filename,
 }: StampSetupSettingsProps) => {
   const { t } = useTranslation();
+  const stampImageWithUrl = useFileWithUrl(
+    parameters.stampType === "image" ? (parameters.stampImage ?? null) : null,
+  );
 
   return (
     <Stack gap="md">
@@ -679,10 +683,10 @@ const StampSetupSettings = ({
           >
             {t("chooseFile", "Choose File")}
           </Button>
-          {parameters.stampImage && (
+          {parameters.stampImage && stampImageWithUrl && (
             <Stack gap="xs">
               <img
-                src={URL.createObjectURL(parameters.stampImage)}
+                src={stampImageWithUrl.url}
                 alt="Selected stamp image"
                 className="max-h-24 w-full object-contain border border-gray-200 rounded bg-gray-50"
               />