feat(backend): Phase 0 项目骨架完成 — 后端/前端/数据库/Docker

- 后端：FastAPI + SQLAlchemy + Alembic，7 张核心表迁移成功
- 前端：Next.js 16 + TailwindCSS 4 + 三端布局（投资人/创始人/Admin）
- 数据库：PostgreSQL 16，7 张核心实体表（tenants/users/companies/monthly_reports/health_scores/risk_events/audit_logs）
- Docker：docker-compose.yml + 前后端 Dockerfile
- 测试：健康检查 4 个测试全部 GREEN
- 文档：README/run.md/AGENTS.md/docs 体系完整

backend/app/models/risk.py

@@ -0,0 +1,43 @@
+"""风险事件模型。
+
+指标越界自动预警 + 人工处理闭环。
+"""
+
+import uuid
+from datetime import datetime, timezone
+
+from sqlalchemy import DateTime, ForeignKey, String, Text
+from sqlalchemy.dialects.postgresql import JSONB
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.database import Base
+
+
+class RiskEvent(Base):
+    """风险事件。"""
+
+    __tablename__ = "risk_events"
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    company_id: Mapped[str] = mapped_column(String(36), ForeignKey("companies.id"), nullable=False, index=True)
+    type: Mapped[str] = mapped_column(String(50), nullable=False, comment="风险类型：financial/operational/org/ai_specific")
+    severity: Mapped[str] = mapped_column(String(20), nullable=False, default="medium", comment="严重程度：low/medium/high/critical")
+    status: Mapped[str] = mapped_column(String(20), nullable=False, default="open", comment="状态：open/assigned/in_progress/resolved/closed")
+    title: Mapped[str] = mapped_column(String(200), nullable=False)
+    description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    evidence_json: Mapped[dict | None] = mapped_column(JSONB, nullable=True, comment="证据链")
+    suggested_action: Mapped[str | None] = mapped_column(Text, nullable=True, comment="建议动作")
+    assigned_to: Mapped[str | None] = mapped_column(String(36), ForeignKey("users.id"), nullable=True)
+    due_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    identified_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
+    )
+    closed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=lambda: datetime.now(timezone.utc),
+        onupdate=lambda: datetime.now(timezone.utc),
+    )