fix: handle initial cover image key in EditPost component and update payload for blog post submission

src/pages/EditPost.tsx

@@ -21,6 +21,7 @@ function EditPost() {
   const [initialContent, setInitialContent] = useState<string | undefined>(undefined);
   const [coverImage, setCoverImage] = useState<string | null>(null);
   const [coverImageKey, setCoverImageKey] = useState<string>('');
+  const [initialCoverImageKey, setInitialCoverImageKey] = useState<string>('');
 
   const [uploadProgress, setUploadProgress] = useState(0);
   const [isUploading, setIsUploading] = useState(false);
@@ -40,7 +41,9 @@ function EditPost() {
         setTitle(fetched.title);
         setInitialContent(fetched.content);
         setCoverImage(fetched.coverImageUrl ?? null);
-        setCoverImageKey(fetched.coverImageKey ?? '');
+        const fetchedCoverKey = fetched.coverImageKey ?? '';
+        setCoverImageKey(fetchedCoverKey);
+        setInitialCoverImageKey(fetchedCoverKey);
       } catch (err) {
         const message = err instanceof Error ? err.message : 'Failed to load post.';
         setLoadError(message);
@@ -111,14 +114,16 @@ function EditPost() {
     setIsSubmitting(true);
 
     try {
+      const coverKeyToSend = coverImageKey || initialCoverImageKey;
+
       const payload: Parameters<typeof updateBlogPost>[0] = {
         postId,
         title: title.trim(),
         content,
       };
 
-      if (coverImageKey) {
-        payload.coverImageKey = coverImageKey;
+      if (coverKeyToSend) {
+        payload.coverImageKey = coverKeyToSend;
       }
 
       await updateBlogPost(payload);