Updated ui and backend

Added Sequential, limited and concurrent downloading and import export buttons

ui/src/app/app.component.sass

@@ -64,4 +64,42 @@ td
 
 .download-progressbar
     width: 12rem
-    margin-left: auto
+    margin-left: auto
+
+.batch-panel
+  margin-top: 15px
+  border: 1px solid #ccc
+  border-radius: 8px
+  padding: 15px
+  background-color: #fff
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1)
+
+.batch-panel-header
+  border-bottom: 1px solid #eee
+  padding-bottom: 8px
+  margin-bottom: 15px
+  h4
+    font-size: 1.5rem
+    margin: 0
+
+.batch-panel-body
+  textarea.form-control
+    resize: vertical
+
+.batch-status
+  font-size: 0.9rem
+  color: #555
+
+.d-flex.my-3
+  margin-top: 1rem
+  margin-bottom: 1rem
+ 
+.modal.fade.show
+  background-color: rgba(0, 0, 0, 0.5)
+
+.modal-header
+  border-bottom: 1px solid #eee
+.modal-body
+  textarea.form-control
+    resize: vertical
+