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.go

@@ -43,6 +43,8 @@ type Group struct {
 	WeeklyLimitUsd *float64 `json:"weekly_limit_usd,omitempty"`
 	// MonthlyLimitUsd holds the value of the "monthly_limit_usd" field.
 	MonthlyLimitUsd *float64 `json:"monthly_limit_usd,omitempty"`
+	// DefaultValidityDays holds the value of the "default_validity_days" field.
+	DefaultValidityDays int `json:"default_validity_days,omitempty"`
 	// Edges holds the relations/edges for other nodes in the graph.
 	// The values are being populated by the GroupQuery when eager-loading is set.
 	Edges        GroupEdges `json:"edges"`
@@ -57,6 +59,8 @@ type GroupEdges struct {
 	RedeemCodes []*RedeemCode `json:"redeem_codes,omitempty"`
 	// Subscriptions holds the value of the subscriptions edge.
 	Subscriptions []*UserSubscription `json:"subscriptions,omitempty"`
+	// UsageLogs holds the value of the usage_logs edge.
+	UsageLogs []*UsageLog `json:"usage_logs,omitempty"`
 	// Accounts holds the value of the accounts edge.
 	Accounts []*Account `json:"accounts,omitempty"`
 	// AllowedUsers holds the value of the allowed_users edge.
@@ -67,7 +71,7 @@ type GroupEdges struct {
 	UserAllowedGroups []*UserAllowedGroup `json:"user_allowed_groups,omitempty"`
 	// loadedTypes holds the information for reporting if a
 	// type was loaded (or requested) in eager-loading or not.
-	loadedTypes [7]bool
+	loadedTypes [8]bool
 }
 
 // APIKeysOrErr returns the APIKeys value or an error if the edge
@@ -97,10 +101,19 @@ func (e GroupEdges) SubscriptionsOrErr() ([]*UserSubscription, error) {
 	return nil, &NotLoadedError{edge: "subscriptions"}
 }
 
+// UsageLogsOrErr returns the UsageLogs value or an error if the edge
+// was not loaded in eager-loading.
+func (e GroupEdges) UsageLogsOrErr() ([]*UsageLog, error) {
+	if e.loadedTypes[3] {
+		return e.UsageLogs, nil
+	}
+	return nil, &NotLoadedError{edge: "usage_logs"}
+}
+
 // AccountsOrErr returns the Accounts value or an error if the edge
 // was not loaded in eager-loading.
 func (e GroupEdges) AccountsOrErr() ([]*Account, error) {
-	if e.loadedTypes[3] {
+	if e.loadedTypes[4] {
 		return e.Accounts, nil
 	}
 	return nil, &NotLoadedError{edge: "accounts"}
@@ -109,7 +122,7 @@ func (e GroupEdges) AccountsOrErr() ([]*Account, error) {
 // AllowedUsersOrErr returns the AllowedUsers value or an error if the edge
 // was not loaded in eager-loading.
 func (e GroupEdges) AllowedUsersOrErr() ([]*User, error) {
-	if e.loadedTypes[4] {
+	if e.loadedTypes[5] {
 		return e.AllowedUsers, nil
 	}
 	return nil, &NotLoadedError{edge: "allowed_users"}
@@ -118,7 +131,7 @@ func (e GroupEdges) AllowedUsersOrErr() ([]*User, error) {
 // AccountGroupsOrErr returns the AccountGroups value or an error if the edge
 // was not loaded in eager-loading.
 func (e GroupEdges) AccountGroupsOrErr() ([]*AccountGroup, error) {
-	if e.loadedTypes[5] {
+	if e.loadedTypes[6] {
 		return e.AccountGroups, nil
 	}
 	return nil, &NotLoadedError{edge: "account_groups"}
@@ -127,7 +140,7 @@ func (e GroupEdges) AccountGroupsOrErr() ([]*AccountGroup, error) {
 // UserAllowedGroupsOrErr returns the UserAllowedGroups value or an error if the edge
 // was not loaded in eager-loading.
 func (e GroupEdges) UserAllowedGroupsOrErr() ([]*UserAllowedGroup, error) {
-	if e.loadedTypes[6] {
+	if e.loadedTypes[7] {
 		return e.UserAllowedGroups, nil
 	}
 	return nil, &NotLoadedError{edge: "user_allowed_groups"}
@@ -142,7 +155,7 @@ func (*Group) scanValues(columns []string) ([]any, error) {
 			values[i] = new(sql.NullBool)
 		case group.FieldRateMultiplier, group.FieldDailyLimitUsd, group.FieldWeeklyLimitUsd, group.FieldMonthlyLimitUsd:
 			values[i] = new(sql.NullFloat64)
-		case group.FieldID:
+		case group.FieldID, group.FieldDefaultValidityDays:
 			values[i] = new(sql.NullInt64)
 		case group.FieldName, group.FieldDescription, group.FieldStatus, group.FieldPlatform, group.FieldSubscriptionType:
 			values[i] = new(sql.NullString)
@@ -252,6 +265,12 @@ func (_m *Group) assignValues(columns []string, values []any) error {
 				_m.MonthlyLimitUsd = new(float64)
 				*_m.MonthlyLimitUsd = value.Float64
 			}
+		case group.FieldDefaultValidityDays:
+			if value, ok := values[i].(*sql.NullInt64); !ok {
+				return fmt.Errorf("unexpected type %T for field default_validity_days", values[i])
+			} else if value.Valid {
+				_m.DefaultValidityDays = int(value.Int64)
+			}
 		default:
 			_m.selectValues.Set(columns[i], values[i])
 		}
@@ -280,6 +299,11 @@ func (_m *Group) QuerySubscriptions() *UserSubscriptionQuery {
 	return NewGroupClient(_m.config).QuerySubscriptions(_m)
 }
 
+// QueryUsageLogs queries the "usage_logs" edge of the Group entity.
+func (_m *Group) QueryUsageLogs() *UsageLogQuery {
+	return NewGroupClient(_m.config).QueryUsageLogs(_m)
+}
+
 // QueryAccounts queries the "accounts" edge of the Group entity.
 func (_m *Group) QueryAccounts() *AccountQuery {
 	return NewGroupClient(_m.config).QueryAccounts(_m)
@@ -371,6 +395,9 @@ func (_m *Group) String() string {
 		builder.WriteString("monthly_limit_usd=")
 		builder.WriteString(fmt.Sprintf("%v", *v))
 	}
+	builder.WriteString(", ")
+	builder.WriteString("default_validity_days=")
+	builder.WriteString(fmt.Sprintf("%v", _m.DefaultValidityDays))
 	builder.WriteByte(')')
 	return builder.String()
 }