Fix: Rename directory to remove & character causing shell issues

Renamed ebook_backend&admin_panel to ebook_backend_admin_panel
  The & character was being interpreted by shell as background
  process operator, causing 'Dockerfile not found' errors in Coolify.

docker-compose.yml

@@ -28,7 +28,7 @@ services:
   # Backend API + Frontend
   backend:
     build:
-      context: ./ebook_backend&admin_panel
+      context: ./ebook_backend_admin_panel
       dockerfile: Dockerfile
     container_name: ebook_backend
     restart: unless-stopped

ebook_backend_admin_panel/admin-backend/translationfile/metadata.txt

@@ -0,0 +1 @@
+demo (1).xlsx