feat(codex): 拆分openai:compact为独立端点，简化Codex请求为透传模式

- 新增openai:compact端点类型(EndpointKind.COMPACT)，独立于openai:cli
- OpenAICompactAdapter继承OpenAICliAdapter，自动标记compact模式
- Codex请求补丁改为纯透传：仅清理内部标记，不再修改客户端payload
- stream_policy支持openai:compact独立策略，compact端点移除stream字段
- candidate_builder支持compact回退到cli端点
- auth_type: vertex_ai重命名为service_account，保持向后兼容
- Vertex Provider新增api_formats与auth_type组合校验
- KeyAllowedModels对话框改为从Provider获取模型，展示provider_model_name
- Dialog内Select组件自动禁用Portal，修复层级遮挡问题
- 新增Codex compact端点回填迁移脚本

frontend/src/components/ui/select-content.vue

@@ -1,5 +1,5 @@
 <template>
-  <SelectPortal>
+  <SelectPortal :disabled="shouldDisablePortal">
     <SelectContentPrimitive
       v-bind="$attrs"
       :class="contentClass"
@@ -23,7 +23,8 @@ import {
   SelectViewport,
 } from 'radix-vue'
 import { cn } from '@/lib/utils'
-import { computed } from 'vue'
+import { computed, inject } from 'vue'
+import { DIALOG_CONTEXT_KEY } from './dialog/context'
 
 interface Props {
   class?: string
@@ -32,6 +33,7 @@ interface Props {
   sideOffset?: number
   align?: 'start' | 'center' | 'end'
   alignOffset?: number
+  disablePortal?: boolean
 }
 
 const props = withDefaults(defineProps<Props>(), {
@@ -41,8 +43,12 @@ const props = withDefaults(defineProps<Props>(), {
   sideOffset: 4,
   align: undefined,
   alignOffset: undefined,
+  disablePortal: false,
 })
 
+const isInsideDialog = inject(DIALOG_CONTEXT_KEY, false)
+const shouldDisablePortal = computed(() => props.disablePortal || isInsideDialog)
+
 const contentClass = computed(() =>
   cn(
     'z-[200] max-h-96 min-w-[8rem] overflow-hidden rounded-2xl border border-border bg-card text-foreground shadow-2xl backdrop-blur-xl pointer-events-auto',