开放多项目大屏免登录访问

需求描述：/admin/display 需要无需管理员登录即可直接查看多项目公开运行状态。

实现思路：新增公开字段白名单接口与独立大屏页面，移除该路由的管理员会话依赖，同时保留 /api/admin/overview 的鉴权并补充隐私、路由和页面回归测试。

验证：Go 全量测试通过；前端 18 个测试文件共 59 项通过，TypeScript 检查通过。

server/internal/httpapi/public.go

@@ -444,6 +444,41 @@ func newDisplayBatchDTO(batch model.CallBatch, tickets []displayTicketDTO) displ
 	}
 }
 
+func publicDisplayProjectView(project map[string]any) map[string]any {
+	return map[string]any{
+		"id":                   project["id"],
+		"name":                 project["name"],
+		"status":               project["status"],
+		"waiting_count":        project["waiting_count"],
+		"waiting_ticket_count": project["waiting_ticket_count"],
+		"waiting_people_count": project["waiting_people_count"],
+		"issued_ticket_count":  project["issued_ticket_count"],
+		"latest_ticket_number": project["latest_ticket_number"],
+		"experienced_people":   project["experienced_people"],
+		"current_batch":        project["current_batch"],
+		"estimated_wait":       project["estimated_wait"],
+		"last_updated_at":      project["last_updated_at"],
+	}
+}
+
+func (s *Server) displayOverview(w http.ResponseWriter, r *http.Request) {
+	var projects []model.Project
+	if err := s.db.WithContext(r.Context()).Order("name ASC").Find(&projects).Error; err != nil {
+		writeError(w, err)
+		return
+	}
+	views := make([]map[string]any, 0, len(projects))
+	for _, project := range projects {
+		projection, _, _, _, _, err := s.adminProjectProjection(r.Context(), project)
+		if err != nil {
+			writeError(w, err)
+			return
+		}
+		views = append(views, publicDisplayProjectView(projection))
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"projects": views, "server_time": s.now()})
+}
+
 func (s *Server) events(w http.ResponseWriter, r *http.Request) {
 	projectID := strings.TrimSpace(r.URL.Query().Get("project_id"))
 	if err := validateUUID(projectID); err != nil {