fix(chat): prevent persistent gaps after activity collapse

Upgrade LegendList to 3.3.10 and patch temporary padding cleanup to compare CSSOM-serialized values. Settle Activity height when React replays an interrupted layout effect.

Validated with 16 padding regressions, 3 collapse lifecycle tests, the UI suite, workspace type-check and lint, and web and VS Code builds.

packages/ui/package.json

@@ -44,7 +44,7 @@
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
     "@dnd-kit/utilities": "^3.2.2",
-    "@legendapp/list": "3.3.8",
+    "@legendapp/list": "3.3.10",
     "@lezer/highlight": "^1.2.3",
     "@opencode-ai/sdk": "1.18.29",
     "@pierre/diffs": "1.3.0-beta.6",