feat: 模型表单新增独立「模型名」字段，不再需要手写 JSON

- 新增 model_name 输入框，自动合并到 extra_params.model
- 编辑时自动提取回显
- 表格列表新增模型名列
- 避免用户遗漏关键的 model 参数导致调用失败

web/src/pages/ModelList.tsx

@@ -51,12 +51,14 @@ export default function ModelList() {
     // 延迟确保 Form DOM 已渲染
     const timer = setTimeout(() => {
       if (editingModel) {
+        const extra = editingModel.extra_params || {};
         form.setFieldsValue({
           name: editingModel.name,
           provider: editingModel.provider,
+          model_name: extra.model || "",
           endpoint: editingModel.endpoint,
           api_key: "",
-          extra_params: JSON.stringify(editingModel.extra_params, null, 2),
+          extra_params: JSON.stringify(extra, null, 2),
           is_enabled: editingModel.is_enabled,
           remark: editingModel.remark,
         });
@@ -81,8 +83,9 @@ export default function ModelList() {
 
       const payload = {
         ...values,
-        extra_params: extraParams,
+        extra_params: { ...extraParams, ...(values.model_name ? { model: values.model_name } : {}) },
       };
+      delete payload.model_name;
 
       if (editingModel) {
         if (!payload.api_key) delete payload.api_key;
@@ -217,6 +220,9 @@ export default function ModelList() {
           <Form.Item name="provider" label="供应商" rules={[{ required: true }]}>
             <Select options={PROVIDERS} />
           </Form.Item>
+          <Form.Item name="model_name" label="模型名" rules={[{ required: true }]}>
+            <Input placeholder="例如 deepseek-chat / gpt-4 / gpt-3.5-turbo" />
+          </Form.Item>
           <Form.Item name="endpoint" label="接口地址" rules={[{ required: true }]}>
             <Input placeholder="https://api.openai.com/v1/chat/completions" />
           </Form.Item>