ui(deploy): hide CheckpointsTable when no past deployments exist

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/src/pages/AppsTab/AppDeploymentPage/AppDeploymentPage.module.css

@@ -113,11 +113,6 @@
   opacity: 0.55;
 }
 
-.checkpointEmpty {
-  color: var(--text-muted);
-  font-size: 13px;
-}
-
 /* Config tab shared */
 .configInline {
   display: flex;

ui/src/pages/AppsTab/AppDeploymentPage/CheckpointsTable.tsx

@@ -29,7 +29,7 @@ export function CheckpointsTable({
     .sort((a, b) => (b.deployedAt ?? '').localeCompare(a.deployedAt ?? ''));
 
   if (checkpoints.length === 0) {
-    return <div className={styles.checkpointEmpty}>No past deployments yet.</div>;
+    return null;
   }
 
   const cap = jarRetentionCount && jarRetentionCount > 0 ? jarRetentionCount : FALLBACK_CAP;