```

feat: 添加数据库迁移脚本并更新Dockerfile配置

- 在Dockerfile中添加alembic配置文件和目录的复制指令
- 更新alembic/env.py注册新的模块模型：events、workflows、writebacks
- 生成完整的初始数据库schema迁移脚本，包含以下表：
  - approval_requests, attendance_records, audit_logs, domain_events
  - expenses, feishu_event_receipts, fund_accounts, legacy_sync_runs
  - official_writeback_runs, performance_metrics, policies, procurements
  - projects, report_push_runs, risk_event_actions, risk_events
  - standards, suppliers, work_reports, work_tasks, workflow_actions
  - workflow_instances等21个数据表结构定义
- 在API路由器中添加新模块的路由：events、workflows、writebacks、observability
```

app/modules/workflows/models.py

@@ -0,0 +1,44 @@
+from datetime import datetime
+
+from sqlalchemy import JSON, DateTime, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.constants import ActorValue
+from app.core.db_base import Base
+from app.core.time import utc_now
+from app.modules.workflows.constants import WorkflowStatus
+
+
+class WorkflowInstance(Base):
+    __tablename__ = "workflow_instances"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    code: Mapped[str] = mapped_column(String(64), unique=True, index=True)
+    workflow_type: Mapped[str] = mapped_column(String(128), index=True)
+    aggregate_type: Mapped[str] = mapped_column(String(128), index=True)
+    aggregate_id: Mapped[str | None] = mapped_column(String(128), nullable=True, index=True)
+    status: Mapped[str] = mapped_column(String(32), default=WorkflowStatus.RUNNING, index=True)
+    actor: Mapped[str] = mapped_column(String(128), default=ActorValue.SYSTEM, index=True)
+    current_step: Mapped[str | None] = mapped_column(String(128), nullable=True)
+    payload: Mapped[dict | None] = mapped_column(JSON, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=utc_now, index=True)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime,
+        default=utc_now,
+        onupdate=utc_now,
+    )
+    completed_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True, index=True)
+
+
+class WorkflowAction(Base):
+    __tablename__ = "workflow_actions"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    code: Mapped[str] = mapped_column(String(64), unique=True, index=True)
+    workflow_code: Mapped[str] = mapped_column(String(64), index=True)
+    action: Mapped[str] = mapped_column(String(128), index=True)
+    actor: Mapped[str] = mapped_column(String(128), default=ActorValue.SYSTEM, index=True)
+    from_status: Mapped[str | None] = mapped_column(String(32), nullable=True)
+    to_status: Mapped[str | None] = mapped_column(String(32), nullable=True)
+    payload: Mapped[dict | None] = mapped_column(JSON, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=utc_now, index=True)