fix the existing note image replacement (#1025)

Fixes the incorrect usage of the `<Img>` component when `previewImage` was a data URL during existing note image replacement.

Author: wonu

app/routes/users+/$username_+/__note-editor.tsx

@@ -201,7 +201,7 @@ function ImageChooser({
 						>
 							{previewImage ? (
 								<div className="relative">
-									{existingImage ? (
+									{existingImage && !previewImage.startsWith('data:') ? (
 										<Img
 											src={previewImage}
 											alt={altText ?? ''}