Update image editing to use original image dimensions

Modify the image editor to load the original image source instead of a preview URL, ensuring accurate dimensions are used for edits and overlays.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/397bca8c-984f-43ff-841a-10897aeb8140/ae4037a0-2a6f-4530-9bac-79b543286bda/Hpj2VzR

client/src/pages/image-editor.tsx

@@ -100,10 +100,11 @@ export default function ImageEditor() {
         throw new Error("Aucune image sélectionnée");
       }
 
-      // Load the image to get its natural dimensions
+      // IMPORTANT: Always load the ORIGINAL image to preserve exact dimensions
+      // Do NOT use previewUrl as it may have filters that change dimensions
       const img = new Image();
       img.crossOrigin = 'anonymous';
-      img.src = previewUrl || selectedMedia.originalUrl;
+      img.src = selectedMedia.originalUrl;
       
       await new Promise((resolve, reject) => {
         img.onload = resolve;