Improve modal scrolling behavior and height constraints for better usability

Web/templates/main_admin.html

@@ -5396,7 +5396,11 @@ document.addEventListener('DOMContentLoaded', ()=>{
     max-width: 880px;
     margin: 4vh auto;
     padding: 0;
-    overflow: hidden;
+    max-height: 92vh;
+    overflow-x: hidden;
+    overflow-y: auto;
+    overscroll-behavior: contain;
+    -webkit-overflow-scrolling: touch;
     border: 1px solid #d8e1eb;
     border-radius: 16px;
     background: var(--ui-surface);
@@ -5645,6 +5649,8 @@ document.addEventListener('DOMContentLoaded', ()=>{
     #item-modal .modal-content {
         width: calc(100vw - 18px);
         margin: 9px auto;
+        max-height: calc(100dvh - 18px);
+        overflow-y: auto;
         border-radius: 13px;
     }