fix(web): keep later thinking below rectification tool steps

BUG-360: stream thinking and tool activity as an ordered trace so later CoT opens under 正在整理 instead of filling the first 思考 block.
Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/app/globals.css

@@ -271,6 +271,13 @@ button:disabled { cursor: default; opacity: .45; }
   gap: var(--space-2);
   min-height: 24px;
 }
+.agent-thinking-step.is-think:has(.message-thinking) {
+  display: block;
+  min-height: 0;
+}
+.agent-thinking-step.is-think .message-thinking {
+  margin-bottom: 0;
+}
 .agent-thinking-marker {
   width: 20px;
   height: 20px;