feat(sora): 对齐 Sora OAuth 流程并隔离网关请求路径

- 新增并接通 Sora 专用 OAuth 接口与 ST/RT 换取能力
- 完成前端 Sora 授权、RT/ST 手动导入与账号创建流程
- 强化 Sora token 恢复、转发日志与网关路由隔离行为
- 补充后端服务层与路由层相关测试覆盖

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

frontend/src/components/admin/account/AccountTestModal.vue

@@ -238,6 +238,11 @@ const loadAvailableModels = async () => {
           availableModels.value.find((m) => m.id === 'gemini-3-flash-preview') ||
           availableModels.value.find((m) => m.id === 'gemini-3-pro-preview')
         selectedModelId.value = preferred?.id || availableModels.value[0].id
+      } else if (props.account.platform === 'sora') {
+        const preferred =
+          availableModels.value.find((m) => m.id === 'gpt-image') ||
+          availableModels.value.find((m) => !m.id.startsWith('prompt-enhance'))
+        selectedModelId.value = preferred?.id || availableModels.value[0].id
       } else {
         // Try to select Sonnet as default, otherwise use first model
         const sonnetModel = availableModels.value.find((m) => m.id.includes('sonnet'))