feat(server): 工程骨架后端——上传 → 解析 → 清单最小链路

- core：配置（prod 拒绝默认密钥 / dev 短信 / 假模型）、租户事务 + 行级安全策略、
  problem+json 错误码、信封加密与签名下载、对象存储、事务内入队、Valkey stream 事件流、权限点
- identity：手机号 HMAC 存储、注册、登录（挤下线需确认，API3）、服务端会话
- billing：额度流水只追加，预扣 / 结算 / 退回，一笔预扣只有一个结局
- document：分片上传、按文件头识别格式、Gotenberg 转换、文字层与稳定句子编号
- checklist：标注规则识别、模型抽取、三道校验、标注类条款规则兜底、重跑对齐
- ai：提示词注册表（extract.substantive v1 来自 S4 v2）、假模型、OpenAI 兼容供应商、ai_call 流水
- 迁移：data-model 基线、套餐、Procrastinate、会话状态函数
- 测试 30 个：租户隔离、额度、失败退回、对象加密、契约一致性
- Compose（含 migrate）、镜像、CI

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/bid_doctor/audit/service.py

@@ -0,0 +1,50 @@
+"""审计：和业务修改在同一个事务里写入，写失败整个操作就失败（架构 §3.10）。"""
+
+from __future__ import annotations
+
+import json
+from typing import Any
+from uuid import UUID
+
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from bid_doctor.audit.models import AuditEvent
+from bid_doctor.core.crypto import sha256
+from bid_doctor.core.db import TenantContext
+from bid_doctor.core.ids import uuid7
+
+
+async def record(
+    session: AsyncSession,
+    ctx: TenantContext,
+    action: str,
+    object_type: str,
+    object_id: UUID | None,
+    *,
+    project_id: UUID | None = None,
+    before: dict[str, Any] | None = None,
+    after: dict[str, Any] | None = None,
+    actor_kind: str = "user",
+) -> None:
+    digest = (
+        sha256(json.dumps([before, after], ensure_ascii=False, sort_keys=True, default=str))
+        if before or after
+        else None
+    )
+    session.add(
+        AuditEvent(
+            id=uuid7(),
+            tenant_id=ctx.tenant_id,
+            actor_kind=actor_kind,
+            actor_user_id=ctx.user_id if actor_kind == "user" else None,
+            actor_name=ctx.actor_name or None,
+            action=action,
+            object_type=object_type,
+            object_id=object_id,
+            project_id=project_id,
+            before=before,
+            after=after,
+            content_digest=digest,
+            request_id=ctx.request_id or None,
+        )
+    )