fix(openai): use live account models in connection tests

backend/internal/handler/admin/account_handler.go

@@ -2656,6 +2656,14 @@ func (h *AccountHandler) GetAvailableModels(c *gin.Context) {
 
 	// Handle OpenAI accounts
 	if account.IsOpenAI() {
+		// Prefer the shared, account-keyed upstream catalog. If discovery fails,
+		// retain the legacy local catalog below so the test dialog remains usable.
+		if h.accountTestService != nil {
+			if models, fetchErr := h.accountTestService.FetchOpenAIAccountModels(c.Request.Context(), account); fetchErr == nil {
+				response.Success(c, models)
+				return
+			}
+		}
 		// OpenAI 自动透传会绕过常规模型改写，测试/模型列表也应回落到默认模型集。
 		if account.IsOpenAIPassthroughEnabled() {
 			response.Success(c, openai.DefaultModels)