Initial commit: backend scaffold, auth, frontend login

- FastAPI + SQLAlchemy async + Alembic + Postgres backend
- Auth: JWT access + rotating refresh tokens, argon2, roles, audit log
- React 19 + Vite frontend: login page, protected route, auth context
- Docker Compose: postgres, redis, migrate, api, worker (placeholder), frontend/nginx

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/app/db/models/user.py

@@ -0,0 +1,74 @@
+"""Пользователи, роли и refresh-токены."""
+
+from __future__ import annotations
+
+import enum
+import uuid
+from datetime import datetime
+
+from sqlalchemy import Boolean, DateTime, Enum, ForeignKey, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.db.base import Base, TimestampMixin, UUIDPrimaryKeyMixin
+
+
+class UserRole(enum.StrEnum):
+    """Роли фиксированы кодом: набор прав завязан на фискальную ответственность."""
+
+    ADMIN = "admin"      # всё, включая админку, кассы и ключи
+    CASHIER = "cashier"  # очередь и пробитие чеков
+    VIEWER = "viewer"    # только чтение
+
+
+class User(UUIDPrimaryKeyMixin, TimestampMixin, Base):
+    __tablename__ = "users"
+
+    email: Mapped[str] = mapped_column(String(320), unique=True, index=True, nullable=False)
+    password_hash: Mapped[str] = mapped_column(String(255), nullable=False)
+    full_name: Mapped[str] = mapped_column(String(255), nullable=False)
+    role: Mapped[UserRole] = mapped_column(
+        Enum(UserRole, name="user_role", values_callable=lambda e: [i.value for i in e]),
+        nullable=False,
+        default=UserRole.CASHIER,
+    )
+    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    last_login_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+
+    refresh_tokens: Mapped[list[RefreshToken]] = relationship(
+        back_populates="user", cascade="all, delete-orphan"
+    )
+
+    def __repr__(self) -> str:
+        return f"<User {self.email} ({self.role.value})>"
+
+
+class RefreshToken(UUIDPrimaryKeyMixin, TimestampMixin, Base):
+    """Выданные refresh-токены.
+
+    Храним SHA-256 хеш, а не сам токен: утечка дампа БД не должна давать
+    возможность войти. Ротация — выдача нового токена с проставлением
+    `replaced_by_id` у старого, что позволяет обнаружить повторное
+    использование уже израсходованного токена.
+    """
+
+    __tablename__ = "refresh_tokens"
+
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("users.id", ondelete="CASCADE"), index=True, nullable=False
+    )
+    token_hash: Mapped[str] = mapped_column(String(64), unique=True, index=True, nullable=False)
+    expires_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+    revoked_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    replaced_by_id: Mapped[uuid.UUID | None] = mapped_column(
+        ForeignKey("refresh_tokens.id", ondelete="SET NULL")
+    )
+    user_agent: Mapped[str | None] = mapped_column(String(512))
+    ip: Mapped[str | None] = mapped_column(String(64))
+
+    user: Mapped[User] = relationship(back_populates="refresh_tokens")
+
+    @property
+    def is_active(self) -> bool:
+        from datetime import UTC
+
+        return self.revoked_at is None and self.expires_at > datetime.now(UTC)