feat: add configurable provider endpoint for codex-api accounts

Add providerEndpoint field (responses/completions/auto) to openai-responses
accounts, allowing admins to specify which API endpoint format the provider
supports. The relay service normalizes request paths based on this config:
- responses (default): routes all requests to /v1/responses
- completions: routes all requests to /v1/chat/completions
- auto: preserves the original request path

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

web/admin-spa/src/components/accounts/AccountForm.vue

@@ -1692,6 +1692,24 @@
                 </p>
               </div>
 
+              <div>
+                <label class="mb-3 block text-sm font-semibold text-gray-700 dark:text-gray-300"
+                  >Provider 端点类型</label
+                >
+                <select
+                  v-model="form.providerEndpoint"
+                  class="form-input w-full border-gray-300 dark:border-gray-600 dark:bg-gray-700 dark:text-gray-200"
+                >
+                  <option value="responses">Responses（推荐）</option>
+                  <option value="completions">Chat Completions</option>
+                  <option value="auto">自动（保持原始路径）</option>
+                </select>
+                <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+                  指定 Provider 支持的端点类型。Responses 会将所有请求路由到 /v1/responses；Chat
+                  Completions 路由到 /v1/chat/completions；自动则保持客户端请求的原始路径
+                </p>
+              </div>
+
               <!-- 限流时长字段 - 隐藏不显示，使用默认值60 -->
               <input v-model.number="form.rateLimitDuration" type="hidden" value="60" />
             </div>
@@ -3440,6 +3458,24 @@
               </p>
             </div>
 
+            <div>
+              <label class="mb-3 block text-sm font-semibold text-gray-700 dark:text-gray-300"
+                >Provider 端点类型</label
+              >
+              <select
+                v-model="form.providerEndpoint"
+                class="form-input w-full border-gray-300 dark:border-gray-600 dark:bg-gray-700 dark:text-gray-200"
+              >
+                <option value="responses">Responses（推荐）</option>
+                <option value="completions">Chat Completions</option>
+                <option value="auto">自动（保持原始路径）</option>
+              </select>
+              <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+                指定 Provider 支持的端点类型。Responses 路由到 /v1/responses；Chat Completions
+                路由到 /v1/chat/completions；自动则保持原始路径
+              </p>
+            </div>
+
             <!-- 限流时长字段 - 隐藏不显示，保持原值 -->
             <input v-model.number="form.rateLimitDuration" type="hidden" />
 
@@ -4272,6 +4308,7 @@ const form = ref({
   endpointType: props.account?.endpointType || 'anthropic',
   // OpenAI-Responses 特定字段
   baseApi: props.account?.baseApi || '',
+  providerEndpoint: props.account?.providerEndpoint || 'responses',
   // Gemini-API 特定字段
   baseUrl: props.account?.baseUrl || 'https://generativelanguage.googleapis.com',
   rateLimitDuration: props.account?.rateLimitDuration || 60,
@@ -5434,6 +5471,7 @@ const createAccount = async () => {
       data.baseApi = form.value.baseApi
       data.apiKey = form.value.apiKey
       data.userAgent = form.value.userAgent || ''
+      data.providerEndpoint = form.value.providerEndpoint || 'responses'
       data.priority = form.value.priority || 50
       data.rateLimitDuration = 60 // 默认值60，不从用户输入获取
       data.dailyQuota = form.value.dailyQuota || 0
@@ -5784,6 +5822,7 @@ const updateAccount = async () => {
         data.apiKey = form.value.apiKey
       }
       data.userAgent = form.value.userAgent || ''
+      data.providerEndpoint = form.value.providerEndpoint || 'responses'
       data.priority = form.value.priority || 50
       // 编辑时不上传 rateLimitDuration，保持原值
       data.dailyQuota = form.value.dailyQuota || 0
@@ -6406,6 +6445,7 @@ watch(
         deploymentName: newAccount.deploymentName || '',
         // OpenAI-Responses 特定字段
         baseApi: newAccount.baseApi || '',
+        providerEndpoint: newAccount.providerEndpoint || 'responses',
         // Gemini-API 特定字段
         baseUrl: newAccount.baseUrl || 'https://generativelanguage.googleapis.com',
         // 额度管理字段