Go: implement ListModels in ZhipuAI driver (#14886)

### What problem does this PR solve?

Fixes #14884

The ZhipuAI Go driver in `internal/entity/models/zhipu-ai.go` had a stub
`ListModels` method that always returned `"zhipu-ai, no such method"`.
The DeepSeek, Gitee, NVIDIA, OpenAI, SiliconFlow, and OpenRouter drivers
in the same package already implement `ListModels` against the
OpenAI-compatible `/models` endpoint, and the model picker UI relies on
it. This PR brings ZhipuAI in line with that pattern.

### Changes

- `internal/entity/models/zhipu-ai.go`: implement
`ZhipuAIModel.ListModels`.
  - Resolve region with default fallback.
- GET `${BaseURL[region]}/${URLSuffix.Models}` (resolves to
`https://open.bigmodel.cn/api/paas/v4/models` with the default region).
- Send `Authorization: Bearer <api_key>` when an API key is configured.
Omit the header when the key is empty, so an unauthenticated caller gets
a clear `401` from upstream.
- Surface non-200 responses with the upstream status line and body,
matching the other Go drivers.
- Parse the response via the package-level `DSModelList` / `DSModel`
types already used by DeepSeek, Gitee, and SiliconFlow.
- When the response includes `owned_by`, render the entry as
`id@owned_by`, matching the convention of Gitee and SiliconFlow.
- `conf/models/zhipu-ai.json`: add `"models": "models"` to `url_suffix`.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

conf/models/zhipu-ai.json

@@ -9,7 +9,8 @@
     "async_result": "async-result",
     "embedding": "embeddings",
     "rerank": "rerank",
-    "files": "files"
+    "files": "files",
+    "models": "models"
   },
   "class": "glm",
   "models": [

internal/entity/models/zhipu-ai.go

@@ -456,7 +456,63 @@ func (z *ZhipuAIModel) Embed(modelName *string, texts []string, apiConfig *APICo
 }
 
 func (z *ZhipuAIModel) ListModels(apiConfig *APIConfig) ([]string, error) {
-	return nil, fmt.Errorf("%s, no such method", z.Name())
+	region := "default"
+	if apiConfig != nil && apiConfig.Region != nil && *apiConfig.Region != "" {
+		region = *apiConfig.Region
+	}
+
+	baseURL := z.BaseURL["default"]
+	if region != "default" {
+		if regional, ok := z.BaseURL[region]; ok && regional != "" {
+			baseURL = regional
+		}
+	}
+	if baseURL == "" {
+		return nil, fmt.Errorf("zhipu-ai: no base URL configured for default region")
+	}
+
+	url := fmt.Sprintf("%s/%s", strings.TrimSuffix(baseURL, "/"), z.URLSuffix.Models)
+
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+	if apiConfig != nil && apiConfig.ApiKey != nil && *apiConfig.ApiKey != "" {
+		req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", *apiConfig.ApiKey))
+	}
+
+	resp, err := z.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to send request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("ZhipuAI models API error: %s, body: %s", resp.Status, string(body))
+	}
+
+	var modelList DSModelList
+	if err = json.Unmarshal(body, &modelList); err != nil {
+		return nil, fmt.Errorf("failed to parse response: %w", err)
+	}
+
+	models := make([]string, 0, len(modelList.Models))
+	for _, model := range modelList.Models {
+		modelName := model.ID
+		if model.OwnedBy != "" {
+			modelName = model.ID + "@" + model.OwnedBy
+		}
+		models = append(models, modelName)
+	}
+
+	return models, nil
 }
 
 func (z *ZhipuAIModel) Balance(apiConfig *APIConfig) (map[string]interface{}, error) {