feat(preview): add traffic signal visualization

.trellis/tasks/08-05-cesium-traffic-signals/task.json

@@ -0,0 +1,26 @@
+{
+  "id": "cesium-traffic-signals",
+  "name": "cesium-traffic-signals",
+  "title": "Cesium 路口信号灯可视化",
+  "description": "",
+  "status": "in_progress",
+  "dev_type": null,
+  "scope": null,
+  "package": null,
+  "priority": "P2",
+  "creator": "dingkang",
+  "assignee": "dingkang",
+  "createdAt": "2026-08-05",
+  "completedAt": null,
+  "branch": null,
+  "base_branch": "main",
+  "worktree_path": null,
+  "commit": null,
+  "pr_url": null,
+  "subtasks": [],
+  "children": [],
+  "parent": null,
+  "relatedFiles": [],
+  "notes": "",
+  "meta": {}
+}