Refactor image URL handling: Update API routes to return image URLs via the API instead of direct paths, ensuring consistency across avatar and background uploads. Introduce normalization functions for avatar and background URLs to maintain compatibility with existing URLs.

hooks/usePreferences.ts

@@ -1,4 +1,5 @@
 import { useEffect, useState, useRef } from "react";
+import { normalizeBackgroundUrl } from "@/lib/avatars";
 
 interface Preferences {
   homeBackground: string | null;
@@ -49,8 +50,10 @@ export function useBackgroundImage(
     if (preferences) {
       const imageKey = `${page}Background` as keyof Preferences;
       const customImage = preferences[imageKey];
-      const targetImage = customImage || defaultImage;
-      
+      const rawImage = customImage || defaultImage;
+      // Normaliser l'URL pour utiliser l'API si nécessaire
+      const targetImage = normalizeBackgroundUrl(rawImage) || defaultImage;
+
       // Ne changer que si l'image est vraiment différente
       if (targetImage !== prevImageRef.current) {
         prevImageRef.current = targetImage;