fix(数据层): 修复数据完整性与仓储一致性问题

## 数据完整性修复 (fix-critical-data-integrity)
- 添加 error_translate.go 统一错误转换层
- 修复 nil 输入和 NotFound 错误处理
- 增强仓储层错误一致性

## 仓储一致性修复 (fix-high-repository-consistency)
- Group schema 添加 default_validity_days 字段
- Account schema 添加 proxy edge 关联
- 新增 UsageLog ent schema 定义
- 修复 UpdateBalance/UpdateConcurrency 受影响行数校验

## 数据卫生修复 (fix-medium-data-hygiene)
- UserSubscription 添加软删除支持 (SoftDeleteMixin)
- RedeemCode/Setting 添加硬删除策略文档
- account_groups/user_allowed_groups 的 created_at 声明 timestamptz
- 停止写入 legacy users.allowed_groups 列
- 新增迁移: 011-014 (索引优化、软删除、孤立数据审计、列清理)

## 测试补充
- 添加 UserSubscription 软删除测试
- 添加迁移回归测试
- 添加 NotFound 错误测试

🤖 Generated with [Claude Code](https://claude.com/claude-code

)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/internal/repository/api_key_repo.go

@@ -318,12 +318,13 @@ func groupEntityToService(g *dbent.Group) *service.Group {
 		RateMultiplier:   g.RateMultiplier,
 		IsExclusive:      g.IsExclusive,
 		Status:           g.Status,
-		SubscriptionType: g.SubscriptionType,
-		DailyLimitUSD:    g.DailyLimitUsd,
-		WeeklyLimitUSD:   g.WeeklyLimitUsd,
-		MonthlyLimitUSD:  g.MonthlyLimitUsd,
-		CreatedAt:        g.CreatedAt,
-		UpdatedAt:        g.UpdatedAt,
+		SubscriptionType:    g.SubscriptionType,
+		DailyLimitUSD:       g.DailyLimitUsd,
+		WeeklyLimitUSD:      g.WeeklyLimitUsd,
+		MonthlyLimitUSD:     g.MonthlyLimitUsd,
+		DefaultValidityDays: g.DefaultValidityDays,
+		CreatedAt:           g.CreatedAt,
+		UpdatedAt:           g.UpdatedAt,
 	}
 }
 

backend/internal/repository/proxy_repo.go

@@ -178,7 +178,7 @@ func (r *proxyRepository) CountAccountsByProxyID(ctx context.Context, proxyID in
 
 // GetAccountCountsForProxies returns a map of proxy ID to account count for all proxies
 func (r *proxyRepository) GetAccountCountsForProxies(ctx context.Context) (counts map[int64]int64, err error) {
-	rows, err := r.sql.QueryContext(ctx, "SELECT proxy_id, COUNT(*) AS count FROM accounts WHERE proxy_id IS NOT NULL GROUP BY proxy_id")
+	rows, err := r.sql.QueryContext(ctx, "SELECT proxy_id, COUNT(*) AS count FROM accounts WHERE proxy_id IS NOT NULL AND deleted_at IS NULL GROUP BY proxy_id")
 	if err != nil {
 		return nil, err
 	}