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/core/security.py

@@ -0,0 +1,46 @@
+"""安全模块：JWT 生成与验证、密码哈希。"""
+
+from datetime import datetime, timedelta, timezone
+from typing import Any
+
+from jose import jwt
+from passlib.context import CryptContext
+
+from app.core.config import settings
+
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+
+def hash_password(password: str) -> str:
+    """密码哈希。"""
+    return pwd_context.hash(password)
+
+
+def verify_password(plain_password: str, hashed_password: str) -> bool:
+    """验证密码。"""
+    return pwd_context.verify(plain_password, hashed_password)
+
+
+def create_access_token(subject: str, extra_claims: dict[str, Any] | None = None) -> str:
+    """生成 JWT access token。"""
+    expire = datetime.now(timezone.utc) + timedelta(
+        minutes=settings.jwt_access_token_ttl_minutes
+    )
+    payload: dict[str, Any] = {"sub": subject, "exp": expire, "type": "access"}
+    if extra_claims:
+        payload.update(extra_claims)
+    return jwt.encode(payload, settings.jwt_secret_key, algorithm=settings.jwt_algorithm)
+
+
+def create_refresh_token(subject: str) -> str:
+    """生成 JWT refresh token。"""
+    expire = datetime.now(timezone.utc) + timedelta(
+        days=settings.jwt_refresh_token_ttl_days
+    )
+    payload = {"sub": subject, "exp": expire, "type": "refresh"}
+    return jwt.encode(payload, settings.jwt_secret_key, algorithm=settings.jwt_algorithm)
+
+
+def decode_token(token: str) -> dict[str, Any]:
+    """解码 JWT token。"""
+    return jwt.decode(token, settings.jwt_secret_key, algorithms=[settings.jwt_algorithm])