refactor: 统一 sqlmodel_ext 用法至官方推荐模式

- 替换 Field(max_length=X) 为 StrX/TextX 类型别名（21 个 sqlmodels 文件）
- 替换 get + 404 检查为 get_exist_one()（17 个路由文件，约 50 处）
- 替换 save + session.refresh 为 save(load=...)
- 替换 session.add + commit 为 save()（dav/provider.py）
- 更新所有依赖至最新版本

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sqlmodels/product.py

@@ -0,0 +1,206 @@
+from decimal import Decimal
+from enum import StrEnum
+from typing import TYPE_CHECKING
+from uuid import UUID
+
+from sqlalchemy import Numeric, BigInteger
+from sqlmodel import Field, Relationship, text
+
+from sqlmodel_ext import SQLModelBase, UUIDTableBaseMixin, Str255
+
+if TYPE_CHECKING:
+    from .order import Order
+    from .redeem import Redeem
+
+
+class ProductType(StrEnum):
+    """商品类型枚举"""
+
+    STORAGE_PACK = "storage_pack"
+    """容量包"""
+
+    GROUP_TIME = "group_time"
+    """用户组时长"""
+
+    SCORE = "score"
+    """积分充值"""
+
+
+class PaymentMethod(StrEnum):
+    """支付方式枚举"""
+
+    ALIPAY = "alipay"
+    """支付宝"""
+
+    WECHAT = "wechat"
+    """微信支付"""
+
+    STRIPE = "stripe"
+    """Stripe"""
+
+    EASYPAY = "easypay"
+    """易支付"""
+
+    CUSTOM = "custom"
+    """自定义支付"""
+
+
+# ==================== DTO 模型 ====================
+
+class ProductBase(SQLModelBase):
+    """商品基础字段"""
+
+    name: str
+    """商品名称"""
+
+    type: ProductType
+    """商品类型"""
+
+    description: str | None = None
+    """商品描述"""
+
+
+class ProductCreateRequest(ProductBase):
+    """创建商品请求 DTO"""
+
+    name: Str255
+    """商品名称"""
+
+    price: Decimal = Field(ge=0, decimal_places=2)
+    """商品价格（元）"""
+
+    is_active: bool = True
+    """是否上架"""
+
+    sort_order: int = Field(default=0, ge=0)
+    """排序权重（越大越靠前）"""
+
+    # storage_pack 专用
+    size: int | None = Field(default=None, ge=0)
+    """容量大小（字节），type=storage_pack 时必填"""
+
+    duration_days: int | None = Field(default=None, ge=1)
+    """有效天数，type=storage_pack/group_time 时必填"""
+
+    # group_time 专用
+    group_id: UUID | None = None
+    """目标用户组UUID，type=group_time 时必填"""
+
+    # score 专用
+    score_amount: int | None = Field(default=None, ge=1)
+    """积分数量，type=score 时必填"""
+
+
+class ProductUpdateRequest(SQLModelBase):
+    """更新商品请求 DTO（所有字段可选）"""
+
+    name: Str255 | None = None
+    """商品名称"""
+
+    description: str | None = None
+    """商品描述"""
+
+    price: Decimal | None = Field(default=None, ge=0, decimal_places=2)
+    """商品价格（元）"""
+
+    is_active: bool | None = None
+    """是否上架"""
+
+    sort_order: int | None = Field(default=None, ge=0)
+    """排序权重"""
+
+    size: int | None = Field(default=None, ge=0)
+    """容量大小（字节）"""
+
+    duration_days: int | None = Field(default=None, ge=1)
+    """有效天数"""
+
+    group_id: UUID | None = None
+    """目标用户组UUID"""
+
+    score_amount: int | None = Field(default=None, ge=1)
+    """积分数量"""
+
+
+class ProductResponse(ProductBase):
+    """商品响应 DTO"""
+
+    id: UUID
+    """商品UUID"""
+
+    price: float
+    """商品价格（元）"""
+
+    is_active: bool
+    """是否上架"""
+
+    sort_order: int
+    """排序权重"""
+
+    size: int | None = None
+    """容量大小（字节）"""
+
+    duration_days: int | None = None
+    """有效天数"""
+
+    group_id: UUID | None = None
+    """目标用户组UUID"""
+
+    score_amount: int | None = None
+    """积分数量"""
+
+
+# ==================== 数据库模型 ====================
+
+class Product(ProductBase, UUIDTableBaseMixin):
+    """商品模型"""
+
+    name: Str255
+    """商品名称"""
+
+    price: Decimal = Field(sa_type=Numeric(12, 2), default=Decimal("0.00"))
+    """商品价格（元）"""
+
+    is_active: bool = Field(default=True, sa_column_kwargs={"server_default": text("true")})
+    """是否上架"""
+
+    sort_order: int = Field(default=0, sa_column_kwargs={"server_default": "0"})
+    """排序权重（越大越靠前）"""
+
+    # storage_pack 专用
+    size: int | None = Field(default=None, sa_type=BigInteger)
+    """容量大小（字节），type=storage_pack 时必填"""
+
+    duration_days: int | None = None
+    """有效天数，type=storage_pack/group_time 时必填"""
+
+    # group_time 专用
+    group_id: UUID | None = Field(default=None, foreign_key="group.id", ondelete="SET NULL")
+    """目标用户组UUID，type=group_time 时必填"""
+
+    # score 专用
+    score_amount: int | None = None
+    """积分数量，type=score 时必填"""
+
+    # 关系
+    orders: list["Order"] = Relationship(back_populates="product")
+    """关联的订单列表"""
+
+    redeems: list["Redeem"] = Relationship(back_populates="product")
+    """关联的兑换码列表"""
+
+    def to_response(self) -> ProductResponse:
+        """转换为响应 DTO"""
+        return ProductResponse(
+            id=self.id,
+            name=self.name,
+            type=self.type,
+            description=self.description,
+            price=float(self.price),
+            is_active=self.is_active,
+            sort_order=self.sort_order,
+            size=self.size,
+            duration_days=self.duration_days,
+            group_id=self.group_id,
+            score_amount=self.score_amount,
+        )