feat(openai): 增加 OAuth 透传开关

- 仅对 Codex CLI 且账号开启时走原样透传（只替换认证）

- 透传模式禁用工具修正/模型替换，并旁路解析 usage 用于计费

- 管理后台增加开关与文案，ops upstream error 记录 passthrough 标记

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

frontend/src/i18n/locales/en.ts

@@ -1531,6 +1531,9 @@ export default {
       openai: {
         baseUrlHint: 'Leave default for official OpenAI API',
         apiKeyHint: 'Your OpenAI API Key',
+        oauthPassthrough: 'Auto passthrough (auth only)',
+        oauthPassthroughDesc:
+          'When enabled, applies to Codex CLI requests only: the gateway forwards request/response as-is and only swaps OAuth auth, while keeping billing/concurrency/audit. Disable to rollback if you hit 4xx or compatibility issues.',
         enableSora: 'Enable Sora simultaneously',
         enableSoraHint: 'Sora uses the same OpenAI account. Enable to create Sora account simultaneously.'
       },

frontend/src/i18n/locales/zh.ts

@@ -1680,6 +1680,9 @@ export default {
       openai: {
         baseUrlHint: '留空使用官方 OpenAI API',
         apiKeyHint: '您的 OpenAI API Key',
+        oauthPassthrough: '自动透传（仅替换认证）',
+        oauthPassthroughDesc:
+          '开启后，仅对 Codex CLI 请求生效：网关将原样透传请求与响应内容，只替换 OAuth 认证并保留计费/并发/审计；如遇 4xx/兼容性问题可关闭回滚。',
         enableSora: '同时启用 Sora',
         enableSoraHint: 'Sora 使用相同的 OpenAI 账号，开启后将同时创建 Sora 平台账号'
       },