style(home): add overflow-y property to upload zone and adjust alignment for files

frontend/src/views/Home.vue

@@ -690,6 +690,7 @@ const startSimulation = () => {
 .upload-zone {
   border: 1px dashed #CCC;
   height: 200px;
+  overflow-y: auto;
   display: flex;
   align-items: center;
   justify-content: center;
@@ -698,6 +699,10 @@ const startSimulation = () => {
   background: #FAFAFA;
 }
 
+.upload-zone.has-files {
+  align-items: flex-start;
+}
+
 .upload-zone:hover {
   background: #F0F0F0;
   border-color: #999;