feat(test,export,headers): 模型测试复用统一运行时、实时进度展示、导出增强与请求头大小写保留

- 模型测试 failover 从手动 FailoverEngine 改为 TaskService.execute_sync_candidates 统一运行时
- 前端新增实时 trace 轮询进度展示（候选状态、测试账号、进度条）
- 用户导出/导入支持明文 Key 优先（版本升至 1.2），新增 email_verified 字段
- SENSITIVE_CREDENTIAL_FIELDS 统一到 provider_ops/types.py，补充 refresh_token
- 请求头大小写保留机制（resolve_header_name_case + HeaderBuilder.add 语义修改）
- Codex envelope 移除合成头部，保留客户端原始请求头
- endpoint_checker 支持自定义超时透传
- 新增 x-forwarded-scheme 到上游丢弃头部列表

tests/unit/test_provider_query_failover_endpoint.py

@@ -2,7 +2,9 @@ from types import SimpleNamespace
 
 from src.api.admin.provider_query import (
     _build_direct_test_candidates,
+    _build_test_attempts_from_candidate_keys,
     _filter_test_candidates_by_endpoint,
+    _resolve_test_effective_model,
 )
 
 
@@ -36,3 +38,54 @@ def test_filter_test_candidates_by_endpoint_keeps_matching_candidates() -> None:
 
     assert {candidate.endpoint.id for candidate in filtered} == {endpoint_a.id}
     assert all(candidate.endpoint.id != endpoint_b.id for candidate in filtered)
+
+
+def test_resolve_test_effective_model_prefers_pool_key_mapping() -> None:
+    provider, endpoint_a, _endpoint_b = _build_provider()
+    candidate = _build_direct_test_candidates(provider, endpoint_id=endpoint_a.id)[0]  # type: ignore[arg-type]
+    pool_key = SimpleNamespace(id="pool-key", _pool_mapping_matched_model="mapped-model")
+    request = SimpleNamespace(mode="global", model_name="gpt-4")
+
+    effective = _resolve_test_effective_model(
+        provider=provider,  # type: ignore[arg-type]
+        candidate=candidate,
+        request=request,  # type: ignore[arg-type]
+        gm_obj=None,
+        key=pool_key,
+    )
+
+    assert effective == "mapped-model"
+
+
+def test_build_test_attempts_from_candidate_keys_includes_retry_index() -> None:
+    candidate_keys = [
+        SimpleNamespace(
+            candidate_index=2,
+            retry_index=1,
+            key_id="key-b",
+            key_name="Key B",
+            auth_type="api_key",
+            status="failed",
+            skip_reason=None,
+            error_message="timeout",
+            status_code=504,
+            latency_ms=1200,
+        )
+    ]
+
+    attempts = _build_test_attempts_from_candidate_keys(
+        candidate_keys=candidate_keys,
+        candidate_meta_by_pair={
+            (2, "key-b"): {
+                "endpoint_api_format": "openai:chat",
+                "endpoint_base_url": "https://example.test/v1",
+                "effective_model": "mapped-model",
+            }
+        },
+        candidate_meta_by_index={},
+    )
+
+    assert len(attempts) == 1
+    assert attempts[0].retry_index == 1
+    assert attempts[0].effective_model == "mapped-model"
+    assert attempts[0].endpoint_api_format == "openai:chat"