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

tests/services/test_provider_transport_codex.py

@@ -64,3 +64,17 @@ def test_codex_openai_cli_uses_compact_suffix_when_context_marked_compact() -> N
     )
     assert url == "https://chatgpt.com/backend-api/codex/responses/compact"
     set_codex_request_context(None)
+
+
+def test_codex_openai_compact_uses_compact_path_without_v1_prefix() -> None:
+    endpoint = _DummyEndpoint(
+        base_url="https://chatgpt.com/backend-api/codex",
+        api_format="openai:compact",
+        provider=SimpleNamespace(provider_type="codex"),
+    )
+    url = build_provider_url(
+        endpoint,  # type: ignore[arg-type]
+        path_params={"model": "ignored"},
+        is_stream=False,
+    )
+    assert url == "https://chatgpt.com/backend-api/codex/responses/compact"