feat(openai): 支持自动透传开关并透传 User-Agent

- OpenAI OAuth/API Key 统一支持自动透传开关，编辑页可开关\n- 透传模式仅替换认证并保留计费/并发/审计，修复 API Key responses 端点拼接\n- Usage 页面显示原始 User-Agent 且不截断，补充回归测试与清单

frontend/src/views/user/UsageView.vue

@@ -302,7 +302,7 @@
           </template>
 
           <template #cell-user_agent="{ row }">
-            <span v-if="row.user_agent" class="text-sm text-gray-600 dark:text-gray-400 max-w-[150px] truncate block" :title="row.user_agent">{{ formatUserAgent(row.user_agent) }}</span>
+            <span v-if="row.user_agent" class="text-sm text-gray-600 dark:text-gray-400 block max-w-[320px] whitespace-normal break-all" :title="row.user_agent">{{ formatUserAgent(row.user_agent) }}</span>
             <span v-else class="text-sm text-gray-400 dark:text-gray-500">-</span>
           </template>
 
@@ -545,16 +545,7 @@ const formatDuration = (ms: number): string => {
 }
 
 const formatUserAgent = (ua: string): string => {
-  // 提取主要客户端标识
-  if (ua.includes('claude-cli')) return ua.match(/claude-cli\/[\d.]+/)?.[0] || 'Claude CLI'
-  if (ua.includes('Cursor')) return 'Cursor'
-  if (ua.includes('VSCode') || ua.includes('vscode')) return 'VS Code'
-  if (ua.includes('Continue')) return 'Continue'
-  if (ua.includes('Cline')) return 'Cline'
-  if (ua.includes('OpenAI')) return 'OpenAI SDK'
-  if (ua.includes('anthropic')) return 'Anthropic SDK'
-  // 截断过长的 UA
-  return ua.length > 30 ? ua.substring(0, 30) + '...' : ua
+  return ua
 }
 
 const formatTokens = (value: number): string => {