feat: add sort toggle and refresh buttons to log/timeline panels

Remove auto-scroll override hack. Add sort order toggle (asc/desc
by time) and manual refresh button to both the application log and
agent events timeline panels on AgentInstance and AgentHealth pages.
Default is descending (newest first); toggling reverses the array.

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

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

@@ -145,6 +145,30 @@
   border-bottom: 1px solid var(--border-subtle);
 }
 
+.headerActions {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.sortBtn,
+.refreshBtn {
+  background: none;
+  border: 1px solid var(--border-subtle);
+  border-radius: var(--radius-sm);
+  color: var(--text-muted);
+  cursor: pointer;
+  font-size: 13px;
+  padding: 2px 6px;
+  line-height: 1;
+}
+
+.sortBtn:hover,
+.refreshBtn:hover {
+  color: var(--text-primary);
+  border-color: var(--amber);
+}
+
 .logToolbar {
   display: flex;
   align-items: center;