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/ent/group/group.go

@@ -41,12 +41,16 @@ const (
 	FieldWeeklyLimitUsd = "weekly_limit_usd"
 	// FieldMonthlyLimitUsd holds the string denoting the monthly_limit_usd field in the database.
 	FieldMonthlyLimitUsd = "monthly_limit_usd"
+	// FieldDefaultValidityDays holds the string denoting the default_validity_days field in the database.
+	FieldDefaultValidityDays = "default_validity_days"
 	// EdgeAPIKeys holds the string denoting the api_keys edge name in mutations.
 	EdgeAPIKeys = "api_keys"
 	// EdgeRedeemCodes holds the string denoting the redeem_codes edge name in mutations.
 	EdgeRedeemCodes = "redeem_codes"
 	// EdgeSubscriptions holds the string denoting the subscriptions edge name in mutations.
 	EdgeSubscriptions = "subscriptions"
+	// EdgeUsageLogs holds the string denoting the usage_logs edge name in mutations.
+	EdgeUsageLogs = "usage_logs"
 	// EdgeAccounts holds the string denoting the accounts edge name in mutations.
 	EdgeAccounts = "accounts"
 	// EdgeAllowedUsers holds the string denoting the allowed_users edge name in mutations.
@@ -78,6 +82,13 @@ const (
 	SubscriptionsInverseTable = "user_subscriptions"
 	// SubscriptionsColumn is the table column denoting the subscriptions relation/edge.
 	SubscriptionsColumn = "group_id"
+	// UsageLogsTable is the table that holds the usage_logs relation/edge.
+	UsageLogsTable = "usage_logs"
+	// UsageLogsInverseTable is the table name for the UsageLog entity.
+	// It exists in this package in order to avoid circular dependency with the "usagelog" package.
+	UsageLogsInverseTable = "usage_logs"
+	// UsageLogsColumn is the table column denoting the usage_logs relation/edge.
+	UsageLogsColumn = "group_id"
 	// AccountsTable is the table that holds the accounts relation/edge. The primary key declared below.
 	AccountsTable = "account_groups"
 	// AccountsInverseTable is the table name for the Account entity.
@@ -120,6 +131,7 @@ var Columns = []string{
 	FieldDailyLimitUsd,
 	FieldWeeklyLimitUsd,
 	FieldMonthlyLimitUsd,
+	FieldDefaultValidityDays,
 }
 
 var (
@@ -173,6 +185,8 @@ var (
 	DefaultSubscriptionType string
 	// SubscriptionTypeValidator is a validator for the "subscription_type" field. It is called by the builders before save.
 	SubscriptionTypeValidator func(string) error
+	// DefaultDefaultValidityDays holds the default value on creation for the "default_validity_days" field.
+	DefaultDefaultValidityDays int
 )
 
 // OrderOption defines the ordering options for the Group queries.
@@ -248,6 +262,11 @@ func ByMonthlyLimitUsd(opts ...sql.OrderTermOption) OrderOption {
 	return sql.OrderByField(FieldMonthlyLimitUsd, opts...).ToFunc()
 }
 
+// ByDefaultValidityDays orders the results by the default_validity_days field.
+func ByDefaultValidityDays(opts ...sql.OrderTermOption) OrderOption {
+	return sql.OrderByField(FieldDefaultValidityDays, opts...).ToFunc()
+}
+
 // ByAPIKeysCount orders the results by api_keys count.
 func ByAPIKeysCount(opts ...sql.OrderTermOption) OrderOption {
 	return func(s *sql.Selector) {
@@ -290,6 +309,20 @@ func BySubscriptions(term sql.OrderTerm, terms ...sql.OrderTerm) OrderOption {
 	}
 }
 
+// ByUsageLogsCount orders the results by usage_logs count.
+func ByUsageLogsCount(opts ...sql.OrderTermOption) OrderOption {
+	return func(s *sql.Selector) {
+		sqlgraph.OrderByNeighborsCount(s, newUsageLogsStep(), opts...)
+	}
+}
+
+// ByUsageLogs orders the results by usage_logs terms.
+func ByUsageLogs(term sql.OrderTerm, terms ...sql.OrderTerm) OrderOption {
+	return func(s *sql.Selector) {
+		sqlgraph.OrderByNeighborTerms(s, newUsageLogsStep(), append([]sql.OrderTerm{term}, terms...)...)
+	}
+}
+
 // ByAccountsCount orders the results by accounts count.
 func ByAccountsCount(opts ...sql.OrderTermOption) OrderOption {
 	return func(s *sql.Selector) {
@@ -366,6 +399,13 @@ func newSubscriptionsStep() *sqlgraph.Step {
 		sqlgraph.Edge(sqlgraph.O2M, false, SubscriptionsTable, SubscriptionsColumn),
 	)
 }
+func newUsageLogsStep() *sqlgraph.Step {
+	return sqlgraph.NewStep(
+		sqlgraph.From(Table, FieldID),
+		sqlgraph.To(UsageLogsInverseTable, FieldID),
+		sqlgraph.Edge(sqlgraph.O2M, false, UsageLogsTable, UsageLogsColumn),
+	)
+}
 func newAccountsStep() *sqlgraph.Step {
 	return sqlgraph.NewStep(
 		sqlgraph.From(Table, FieldID),

backend/ent/group/where.go

@@ -120,6 +120,11 @@ func MonthlyLimitUsd(v float64) predicate.Group {
 	return predicate.Group(sql.FieldEQ(FieldMonthlyLimitUsd, v))
 }
 
+// DefaultValidityDays applies equality check predicate on the "default_validity_days" field. It's identical to DefaultValidityDaysEQ.
+func DefaultValidityDays(v int) predicate.Group {
+	return predicate.Group(sql.FieldEQ(FieldDefaultValidityDays, v))
+}
+
 // CreatedAtEQ applies the EQ predicate on the "created_at" field.
 func CreatedAtEQ(v time.Time) predicate.Group {
 	return predicate.Group(sql.FieldEQ(FieldCreatedAt, v))
@@ -785,6 +790,46 @@ func MonthlyLimitUsdNotNil() predicate.Group {
 	return predicate.Group(sql.FieldNotNull(FieldMonthlyLimitUsd))
 }
 
+// DefaultValidityDaysEQ applies the EQ predicate on the "default_validity_days" field.
+func DefaultValidityDaysEQ(v int) predicate.Group {
+	return predicate.Group(sql.FieldEQ(FieldDefaultValidityDays, v))
+}
+
+// DefaultValidityDaysNEQ applies the NEQ predicate on the "default_validity_days" field.
+func DefaultValidityDaysNEQ(v int) predicate.Group {
+	return predicate.Group(sql.FieldNEQ(FieldDefaultValidityDays, v))
+}
+
+// DefaultValidityDaysIn applies the In predicate on the "default_validity_days" field.
+func DefaultValidityDaysIn(vs ...int) predicate.Group {
+	return predicate.Group(sql.FieldIn(FieldDefaultValidityDays, vs...))
+}
+
+// DefaultValidityDaysNotIn applies the NotIn predicate on the "default_validity_days" field.
+func DefaultValidityDaysNotIn(vs ...int) predicate.Group {
+	return predicate.Group(sql.FieldNotIn(FieldDefaultValidityDays, vs...))
+}
+
+// DefaultValidityDaysGT applies the GT predicate on the "default_validity_days" field.
+func DefaultValidityDaysGT(v int) predicate.Group {
+	return predicate.Group(sql.FieldGT(FieldDefaultValidityDays, v))
+}
+
+// DefaultValidityDaysGTE applies the GTE predicate on the "default_validity_days" field.
+func DefaultValidityDaysGTE(v int) predicate.Group {
+	return predicate.Group(sql.FieldGTE(FieldDefaultValidityDays, v))
+}
+
+// DefaultValidityDaysLT applies the LT predicate on the "default_validity_days" field.
+func DefaultValidityDaysLT(v int) predicate.Group {
+	return predicate.Group(sql.FieldLT(FieldDefaultValidityDays, v))
+}
+
+// DefaultValidityDaysLTE applies the LTE predicate on the "default_validity_days" field.
+func DefaultValidityDaysLTE(v int) predicate.Group {
+	return predicate.Group(sql.FieldLTE(FieldDefaultValidityDays, v))
+}
+
 // HasAPIKeys applies the HasEdge predicate on the "api_keys" edge.
 func HasAPIKeys() predicate.Group {
 	return predicate.Group(func(s *sql.Selector) {
@@ -854,6 +899,29 @@ func HasSubscriptionsWith(preds ...predicate.UserSubscription) predicate.Group {
 	})
 }
 
+// HasUsageLogs applies the HasEdge predicate on the "usage_logs" edge.
+func HasUsageLogs() predicate.Group {
+	return predicate.Group(func(s *sql.Selector) {
+		step := sqlgraph.NewStep(
+			sqlgraph.From(Table, FieldID),
+			sqlgraph.Edge(sqlgraph.O2M, false, UsageLogsTable, UsageLogsColumn),
+		)
+		sqlgraph.HasNeighbors(s, step)
+	})
+}
+
+// HasUsageLogsWith applies the HasEdge predicate on the "usage_logs" edge with a given conditions (other predicates).
+func HasUsageLogsWith(preds ...predicate.UsageLog) predicate.Group {
+	return predicate.Group(func(s *sql.Selector) {
+		step := newUsageLogsStep()
+		sqlgraph.HasNeighborsWith(s, step, func(s *sql.Selector) {
+			for _, p := range preds {
+				p(s)
+			}
+		})
+	})
+}
+
 // HasAccounts applies the HasEdge predicate on the "accounts" edge.
 func HasAccounts() predicate.Group {
 	return predicate.Group(func(s *sql.Selector) {