fix(candidate): 夹具用产品探针证空并复用真实索引 mapping

首轮试跑暴露三处夹具缺陷（都在 test-only 文件里，产品代码未动）：
- 目标骨架只核 knowledge_bases：最小夹具 schema 没有 tenants 表，改为按 KB 行数与
  产品 ScopeContentEmpty 的十表计数证空；
- 运行期索引曾把 GET _mapping 的结果再包一层 mappings，ES 400；
  现在直接回放原 mapping 文档（properties 层级与封存时完全一致）；
- 目标指纹改在夹具分配桶名之后用同一份 env 计算，运行器再把桶名写进 API/worker env。

试跑两次均按 cleanup_empty_target_ui.py 精确清理并读回（resources 全不存在）。

internal/releaseadapter/v071/candidate_ui_fixture_test.go

@@ -91,15 +91,12 @@ UPDATE knowledge_bases SET embedding_model_id='candidate-model',vector_store_id=
 			t.Fatalf("candidate target %s has %d rows in scope; the target must be empty before delivery", table, n)
 		}
 	}
-	var kbRows, tenantRows int64
+	var kbRows int64
 	if err := fx.pool.QueryRow(ctx, `SELECT count(*) FROM knowledge_bases WHERE id=$1 AND tenant_id=$2`, wsTargetKB, wsTargetTenant).Scan(&kbRows); err != nil {
 		t.Fatal(err)
 	}
-	if err := fx.pool.QueryRow(ctx, `SELECT count(*) FROM tenants WHERE id=$1`, wsTargetTenant).Scan(&tenantRows); err != nil {
-		t.Fatal(err)
-	}
-	if kbRows != 1 || tenantRows < 1 {
-		t.Fatalf("empty target still needs its KB/tenant skeleton: kb=%d tenants=%d", kbRows, tenantRows)
+	if kbRows != 1 {
+		t.Fatalf("empty target still needs its KB skeleton: knowledge_bases rows=%d", kbRows)
 	}
 
 	mapping, err := fx.target(t).Search().MappingSHA256(ctx)
@@ -211,8 +208,8 @@ UPDATE knowledge_bases SET embedding_model_id='candidate-model',vector_store_id=
 		"target_fingerprint": fingerprint,
 		"target": map[string]any{"tenant_id": wsTargetTenant, "knowledge_base_id": wsTargetKB,
 			"database": os.Getenv("KG_LIBRARY_TEST_DATABASE_URL") != "", "empty_probe_counts": counts,
-			"knowledge_bases_rows": kbRows, "tenants_rows": tenantRows,
-			"note": "KB/tenant 骨架存在、十表内容为 0：这是首次发布的空目标，不是'没有目标'"},
+			"knowledge_bases_rows": kbRows,
+			"note":                 "KB 骨架存在、十表内容为 0：这是首次发布的空目标，不是'没有目标'"},
 		"runtime_index":          runtimeIndex,
 		"mapping_sha256":         mapping,
 		"runtime_mapping_sha256": runtimeMapping,
@@ -347,7 +344,7 @@ func candidateCreateIndex(ctx context.Context, base, index string, body map[stri
 			return fmt.Errorf("runtime index %s already exists: refusing to reuse an unknown index", index)
 		}
 	}
-	payload, err := json.Marshal(map[string]any{"mappings": body})
+	payload, err := json.Marshal(body)
 	if err != nil {
 		return err
 	}