Fix double vertical scrollbar on documents/schemas/channels pages (#281)

Remove duplicate overflow-y from nested list containers so only
the document table scrolls, eliminating the extra page-level scrollbar.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: hackerwins

src/assets/styles/pages/admin_project_document.scss

@@ -46,7 +46,8 @@
   .channel_list_area {
     display: flex;
     flex-direction: column;
-    overflow-y: auto;
+    flex: 1;
+    min-height: 0;
     padding-top: variables.$spacing_48;
 
     @include mixins-lib.tabletStart() {
@@ -71,7 +72,8 @@
 
   .document_table {
     overflow-y: auto;
-    height: 100%;
+    flex: 1;
+    min-height: 0;
     margin-top: variables.$spacing_16;
 
     @include mixins-lib.tabletStart() {