feat: 扩展 Model 设置功能

- 添加 Embedding 模型类型支持
- 优化模型设置表单样式

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/views/settings/useModelSettings.ts

@@ -27,6 +27,8 @@ export function useModelSettings() {
 
   // 默认 Base URL 映射
   const defaultBaseUrls: Record<string, string> = {
+    OpenAI: 'http://localhost:1234/v1',
+    Ollama: 'http://localhost:11434',
     ali: 'https://dashscope.aliyuncs.com/compatible-mode/v1',
   }
 
@@ -120,6 +122,7 @@ export function useModelSettings() {
         body: JSON.stringify({
           provider: newModelForm.value.provider,
           model: newModelForm.value.model,
+          model_type: newModelForm.value.modelType || 'chat',
           api_key: newModelForm.value.apiKey,
           base_url: newModelForm.value.baseUrl,
           api_endpoint: newModelForm.value.apiEndpoint,