fix(studio): hide sidebar group until token resolves; remove VITE_STUDIO_ENABLED

- workspace-nav-studio: return null while isLoading so the "工作室" group
  no longer briefly mounts and then unmounts when getTokenByEmail returns
  "用户不存在" (404). Skeleton branch became dead code, removed.
- studio/hooks: switch all three token queries from retry: 1 to false —
  account-not-found is a permanent error; retry just doubled isError latency.
- env: drop VITE_STUDIO_ENABLED everywhere (env.ts + 7 env files +
  workspace-nav-chat-list). Sidebar availability is now decided at runtime
  by token success instead of a build-time flag.
- env: add VITE_AIPI_PRESENT_URL + VITE_AIPI_KNOWES_URL for the document
  upload popup's A-system jump + B-system knowledge iframe; reuse the
  existing VITE_AIPI_KNOWLEDGE_URL for the Y-system iframe.
- document-upload-popup: replace 8 hardcoded URLs (6 present, 1 knowes,
  1 knowlibrary) with the corresponding env vars.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend-web/.env.sit

@@ -22,14 +22,16 @@ VITE_AIPI_MOPECHAT_URL=https://ch1.b.sit.4.cn/likun_b1_mope
 # 工作室/笔记本后端接口（侧边栏“工作室”列表、笔记本详情等都走这里，不是 VITE_NOTE_API_BASE_URL）
 VITE_AIPI_BACKENP_URL=https://knowledgetoolserver.b.sit.4.cn
 VITE_AIPI_CONSUMER_URL=https://ch1.b.sit.4.cn/consumer
+# A 系统跳转地址（人物/组织/事件等列表项打开链接）
+VITE_AIPI_PRESENT_URL=http://present.a.sit.4.cn/present/domain
+# B 系统知识库 iframe 根地址
+VITE_AIPI_KNOWES_URL=https://ch1.b.sit.4.cn/knowes
 # MaxKey 鉴权（getTokenByOnlineTicket）
 VITE_AUTH_BASE_URL=https://auth.y.sit.4.cn
 VITE_AIPI_PGLINKTO_URL=https://pg.b.sit.4.cn
 VITE_AIPI_XKLINKTO_URL=https://kz.b.sit.4.cn
 # 工作室/笔记本前端地址（用于 auth/callback 等跳转）
 VITE_AIPI_FRONTEND_URL=https://knowledgetoolserver.b.sit.4.cn
-# 工作室侧边栏显示开关；仅控制入口显示，展开内容仍依赖 notebook 接口成功返回数据
-VITE_STUDIO_ENABLED=true
 
 # 可选：Canvas 独立 LangGraph 地址
 # VITE_CANVAS_LANGGRAPH_BASE_URL=