feat(backend): T1.1 认证与权限 — 注册/登录/刷新/获取用户

- 后端：auth 路由（register/login/refresh/me）+ JWT + bcrypt 密码哈希
- 依赖注入：get_current_user + require_role 角色权限校验
- 跨数据库兼容：JSONBType（PG 用 JSONB，SQLite 用 JSON）
- 测试：11 个认证测试 + 4 个健康检查测试 = 15 passed

backend/app/models/risk.py

@@ -7,10 +7,10 @@ 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
+from app.core.types import JSONBType
 
 
 class RiskEvent(Base):
@@ -25,7 +25,7 @@ class RiskEvent(Base):
     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")
+    evidence_json: Mapped[dict | None] = mapped_column(JSONBType, 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)