fix(ui): make exchange table fill page height with vertical scroll

ui/src/components/LayoutShell.tsx

@@ -268,7 +268,7 @@ function LayoutContent() {
         <ContentTabs active={scope.tab} onChange={setTab} scope={scope} />
       )}
 
-      <main style={{ flex: 1, overflow: 'auto', padding: isAdminPage ? '1.5rem' : 0 }}>
+      <main style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden', padding: isAdminPage ? '1.5rem' : 0 }}>
         <Outlet />
       </main>
     </AppShell>

ui/src/pages/Dashboard/Dashboard.module.css

@@ -1,23 +1,36 @@
-/* Scrollable content area */
+/* Scrollable content area — fills remaining height */
 .content {
+  display: flex;
+  flex-direction: column;
   flex: 1;
-  overflow-y: auto;
+  min-height: 0;
   min-width: 0;
   background: var(--bg-body);
 }
 
+/* Table section — stretches to fill and scrolls internally */
+
+
 /* Filter bar spacing */
 .filterBar {
   margin-bottom: 16px;
 }
 
-/* Table section */
 .tableSection {
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+  min-height: 0;
   background: var(--bg-surface);
-  border-bottom: 1px solid var(--border-subtle);
   overflow: hidden;
 }
 
+.tableScroll {
+  flex: 1;
+  min-height: 0;
+  overflow-y: auto;
+}
+
 .tableHeader {
   display: flex;
   align-items: center;

ui/src/pages/Dashboard/Dashboard.tsx

@@ -267,6 +267,7 @@ export default function Dashboard() {
             </div>
           </div>
 
+          <div className={styles.tableScroll}>
             <DataTable
               columns={columns}
               data={rows}
@@ -290,6 +291,7 @@ export default function Dashboard() {
             />
           </div>
         </div>
+      </div>
     </>
   )
 }