feat(frontend): redesign connections management view

Upgrade the connections page to a two-pane management console
with a scope tree, search toolbar, type filters, and a denser
results list while keeping existing connect, edit, test, and
batch actions available.

Also archive the completed ANSI terminal effects follow-up and
sync frontend/backend knowledge base records for the new default
terminal text effect behavior.

.helloagents/archive/2026-03/202603250636_connections-view-tree-search-redesign/.status.json

@@ -0,0 +1 @@
+{"status":"completed","completed":5,"failed":0,"pending":0,"total":5,"done":5,"percent":100,"current":"已完成连接管理页双栏重构与前端构建验证，等待归档","updated_at":"2026-03-25 06:45:00"}