fix: match log/timeline height, DESC sort with scroll-to-top

Give logCard the same max-height and flex layout as timelineCard so
both columns are equal height. Revert .toReversed() so events stay
in DESC order (newest at top). Override EventFeed's auto-scroll-to-
bottom with a requestAnimationFrame that resets scrollTop to 0 after
mount, keeping newest entries visible at the top of both panels.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/AgentInstance/AgentInstance.module.css

@@ -132,6 +132,9 @@
   border-radius: var(--radius-lg);
   box-shadow: var(--shadow-card);
   overflow: hidden;
+  display: flex;
+  flex-direction: column;
+  max-height: 420px;
 }
 
 .logHeader {