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_create.go

@@ -15,6 +15,7 @@ import (
 	"github.com/Wei-Shaw/sub2api/ent/apikey"
 	"github.com/Wei-Shaw/sub2api/ent/group"
 	"github.com/Wei-Shaw/sub2api/ent/redeemcode"
+	"github.com/Wei-Shaw/sub2api/ent/usagelog"
 	"github.com/Wei-Shaw/sub2api/ent/user"
 	"github.com/Wei-Shaw/sub2api/ent/usersubscription"
 )
@@ -201,6 +202,20 @@ func (_c *GroupCreate) SetNillableMonthlyLimitUsd(v *float64) *GroupCreate {
 	return _c
 }
 
+// SetDefaultValidityDays sets the "default_validity_days" field.
+func (_c *GroupCreate) SetDefaultValidityDays(v int) *GroupCreate {
+	_c.mutation.SetDefaultValidityDays(v)
+	return _c
+}
+
+// SetNillableDefaultValidityDays sets the "default_validity_days" field if the given value is not nil.
+func (_c *GroupCreate) SetNillableDefaultValidityDays(v *int) *GroupCreate {
+	if v != nil {
+		_c.SetDefaultValidityDays(*v)
+	}
+	return _c
+}
+
 // AddAPIKeyIDs adds the "api_keys" edge to the ApiKey entity by IDs.
 func (_c *GroupCreate) AddAPIKeyIDs(ids ...int64) *GroupCreate {
 	_c.mutation.AddAPIKeyIDs(ids...)
@@ -246,6 +261,21 @@ func (_c *GroupCreate) AddSubscriptions(v ...*UserSubscription) *GroupCreate {
 	return _c.AddSubscriptionIDs(ids...)
 }
 
+// AddUsageLogIDs adds the "usage_logs" edge to the UsageLog entity by IDs.
+func (_c *GroupCreate) AddUsageLogIDs(ids ...int64) *GroupCreate {
+	_c.mutation.AddUsageLogIDs(ids...)
+	return _c
+}
+
+// AddUsageLogs adds the "usage_logs" edges to the UsageLog entity.
+func (_c *GroupCreate) AddUsageLogs(v ...*UsageLog) *GroupCreate {
+	ids := make([]int64, len(v))
+	for i := range v {
+		ids[i] = v[i].ID
+	}
+	return _c.AddUsageLogIDs(ids...)
+}
+
 // AddAccountIDs adds the "accounts" edge to the Account entity by IDs.
 func (_c *GroupCreate) AddAccountIDs(ids ...int64) *GroupCreate {
 	_c.mutation.AddAccountIDs(ids...)
@@ -347,6 +377,10 @@ func (_c *GroupCreate) defaults() error {
 		v := group.DefaultSubscriptionType
 		_c.mutation.SetSubscriptionType(v)
 	}
+	if _, ok := _c.mutation.DefaultValidityDays(); !ok {
+		v := group.DefaultDefaultValidityDays
+		_c.mutation.SetDefaultValidityDays(v)
+	}
 	return nil
 }
 
@@ -396,6 +430,9 @@ func (_c *GroupCreate) check() error {
 			return &ValidationError{Name: "subscription_type", err: fmt.Errorf(`ent: validator failed for field "Group.subscription_type": %w`, err)}
 		}
 	}
+	if _, ok := _c.mutation.DefaultValidityDays(); !ok {
+		return &ValidationError{Name: "default_validity_days", err: errors.New(`ent: missing required field "Group.default_validity_days"`)}
+	}
 	return nil
 }
 
@@ -475,6 +512,10 @@ func (_c *GroupCreate) createSpec() (*Group, *sqlgraph.CreateSpec) {
 		_spec.SetField(group.FieldMonthlyLimitUsd, field.TypeFloat64, value)
 		_node.MonthlyLimitUsd = &value
 	}
+	if value, ok := _c.mutation.DefaultValidityDays(); ok {
+		_spec.SetField(group.FieldDefaultValidityDays, field.TypeInt, value)
+		_node.DefaultValidityDays = value
+	}
 	if nodes := _c.mutation.APIKeysIDs(); len(nodes) > 0 {
 		edge := &sqlgraph.EdgeSpec{
 			Rel:     sqlgraph.O2M,
@@ -523,6 +564,22 @@ func (_c *GroupCreate) createSpec() (*Group, *sqlgraph.CreateSpec) {
 		}
 		_spec.Edges = append(_spec.Edges, edge)
 	}
+	if nodes := _c.mutation.UsageLogsIDs(); len(nodes) > 0 {
+		edge := &sqlgraph.EdgeSpec{
+			Rel:     sqlgraph.O2M,
+			Inverse: false,
+			Table:   group.UsageLogsTable,
+			Columns: []string{group.UsageLogsColumn},
+			Bidi:    false,
+			Target: &sqlgraph.EdgeTarget{
+				IDSpec: sqlgraph.NewFieldSpec(usagelog.FieldID, field.TypeInt64),
+			},
+		}
+		for _, k := range nodes {
+			edge.Target.Nodes = append(edge.Target.Nodes, k)
+		}
+		_spec.Edges = append(_spec.Edges, edge)
+	}
 	if nodes := _c.mutation.AccountsIDs(); len(nodes) > 0 {
 		edge := &sqlgraph.EdgeSpec{
 			Rel:     sqlgraph.M2M,
@@ -813,6 +870,24 @@ func (u *GroupUpsert) ClearMonthlyLimitUsd() *GroupUpsert {
 	return u
 }
 
+// SetDefaultValidityDays sets the "default_validity_days" field.
+func (u *GroupUpsert) SetDefaultValidityDays(v int) *GroupUpsert {
+	u.Set(group.FieldDefaultValidityDays, v)
+	return u
+}
+
+// UpdateDefaultValidityDays sets the "default_validity_days" field to the value that was provided on create.
+func (u *GroupUpsert) UpdateDefaultValidityDays() *GroupUpsert {
+	u.SetExcluded(group.FieldDefaultValidityDays)
+	return u
+}
+
+// AddDefaultValidityDays adds v to the "default_validity_days" field.
+func (u *GroupUpsert) AddDefaultValidityDays(v int) *GroupUpsert {
+	u.Add(group.FieldDefaultValidityDays, v)
+	return u
+}
+
 // UpdateNewValues updates the mutable fields using the new values that were set on create.
 // Using this option is equivalent to using:
 //
@@ -1089,6 +1164,27 @@ func (u *GroupUpsertOne) ClearMonthlyLimitUsd() *GroupUpsertOne {
 	})
 }
 
+// SetDefaultValidityDays sets the "default_validity_days" field.
+func (u *GroupUpsertOne) SetDefaultValidityDays(v int) *GroupUpsertOne {
+	return u.Update(func(s *GroupUpsert) {
+		s.SetDefaultValidityDays(v)
+	})
+}
+
+// AddDefaultValidityDays adds v to the "default_validity_days" field.
+func (u *GroupUpsertOne) AddDefaultValidityDays(v int) *GroupUpsertOne {
+	return u.Update(func(s *GroupUpsert) {
+		s.AddDefaultValidityDays(v)
+	})
+}
+
+// UpdateDefaultValidityDays sets the "default_validity_days" field to the value that was provided on create.
+func (u *GroupUpsertOne) UpdateDefaultValidityDays() *GroupUpsertOne {
+	return u.Update(func(s *GroupUpsert) {
+		s.UpdateDefaultValidityDays()
+	})
+}
+
 // Exec executes the query.
 func (u *GroupUpsertOne) Exec(ctx context.Context) error {
 	if len(u.create.conflict) == 0 {
@@ -1531,6 +1627,27 @@ func (u *GroupUpsertBulk) ClearMonthlyLimitUsd() *GroupUpsertBulk {
 	})
 }
 
+// SetDefaultValidityDays sets the "default_validity_days" field.
+func (u *GroupUpsertBulk) SetDefaultValidityDays(v int) *GroupUpsertBulk {
+	return u.Update(func(s *GroupUpsert) {
+		s.SetDefaultValidityDays(v)
+	})
+}
+
+// AddDefaultValidityDays adds v to the "default_validity_days" field.
+func (u *GroupUpsertBulk) AddDefaultValidityDays(v int) *GroupUpsertBulk {
+	return u.Update(func(s *GroupUpsert) {
+		s.AddDefaultValidityDays(v)
+	})
+}
+
+// UpdateDefaultValidityDays sets the "default_validity_days" field to the value that was provided on create.
+func (u *GroupUpsertBulk) UpdateDefaultValidityDays() *GroupUpsertBulk {
+	return u.Update(func(s *GroupUpsert) {
+		s.UpdateDefaultValidityDays()
+	})
+}
+
 // Exec executes the query.
 func (u *GroupUpsertBulk) Exec(ctx context.Context) error {
 	if u.create.err != nil {