Made docker's build-kit optional.

scripts/manager.sh

@@ -49,7 +49,16 @@ build_docker_image() {
         return 1
     fi
     echo "Building Docker image..."
-    export DOCKER_BUILDKIT=1
+    
+    # Check if BuildKit is installed
+    if docker buildx version &>/dev/null; then
+        echo "BuildKit detected. Enabling BuildKit..."
+        export DOCKER_BUILDKIT=1
+    else
+        echo "BuildKit not found. Using legacy builder..."
+        export DOCKER_BUILDKIT=0
+    fi
+
     if docker build -t "$IMAGE_NAME" .; then
         echo "Docker image built successfully."
         return 0