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/user_update.go

@@ -15,6 +15,7 @@ import (
 	"github.com/Wei-Shaw/sub2api/ent/group"
 	"github.com/Wei-Shaw/sub2api/ent/predicate"
 	"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"
 )
@@ -273,6 +274,21 @@ func (_u *UserUpdate) AddAllowedGroups(v ...*Group) *UserUpdate {
 	return _u.AddAllowedGroupIDs(ids...)
 }
 
+// AddUsageLogIDs adds the "usage_logs" edge to the UsageLog entity by IDs.
+func (_u *UserUpdate) AddUsageLogIDs(ids ...int64) *UserUpdate {
+	_u.mutation.AddUsageLogIDs(ids...)
+	return _u
+}
+
+// AddUsageLogs adds the "usage_logs" edges to the UsageLog entity.
+func (_u *UserUpdate) AddUsageLogs(v ...*UsageLog) *UserUpdate {
+	ids := make([]int64, len(v))
+	for i := range v {
+		ids[i] = v[i].ID
+	}
+	return _u.AddUsageLogIDs(ids...)
+}
+
 // Mutation returns the UserMutation object of the builder.
 func (_u *UserUpdate) Mutation() *UserMutation {
 	return _u.mutation
@@ -383,6 +399,27 @@ func (_u *UserUpdate) RemoveAllowedGroups(v ...*Group) *UserUpdate {
 	return _u.RemoveAllowedGroupIDs(ids...)
 }
 
+// ClearUsageLogs clears all "usage_logs" edges to the UsageLog entity.
+func (_u *UserUpdate) ClearUsageLogs() *UserUpdate {
+	_u.mutation.ClearUsageLogs()
+	return _u
+}
+
+// RemoveUsageLogIDs removes the "usage_logs" edge to UsageLog entities by IDs.
+func (_u *UserUpdate) RemoveUsageLogIDs(ids ...int64) *UserUpdate {
+	_u.mutation.RemoveUsageLogIDs(ids...)
+	return _u
+}
+
+// RemoveUsageLogs removes "usage_logs" edges to UsageLog entities.
+func (_u *UserUpdate) RemoveUsageLogs(v ...*UsageLog) *UserUpdate {
+	ids := make([]int64, len(v))
+	for i := range v {
+		ids[i] = v[i].ID
+	}
+	return _u.RemoveUsageLogIDs(ids...)
+}
+
 // Save executes the query and returns the number of nodes affected by the update operation.
 func (_u *UserUpdate) Save(ctx context.Context) (int, error) {
 	if err := _u.defaults(); err != nil {
@@ -751,6 +788,51 @@ func (_u *UserUpdate) sqlSave(ctx context.Context) (_node int, err error) {
 		edge.Target.Fields = specE.Fields
 		_spec.Edges.Add = append(_spec.Edges.Add, edge)
 	}
+	if _u.mutation.UsageLogsCleared() {
+		edge := &sqlgraph.EdgeSpec{
+			Rel:     sqlgraph.O2M,
+			Inverse: false,
+			Table:   user.UsageLogsTable,
+			Columns: []string{user.UsageLogsColumn},
+			Bidi:    false,
+			Target: &sqlgraph.EdgeTarget{
+				IDSpec: sqlgraph.NewFieldSpec(usagelog.FieldID, field.TypeInt64),
+			},
+		}
+		_spec.Edges.Clear = append(_spec.Edges.Clear, edge)
+	}
+	if nodes := _u.mutation.RemovedUsageLogsIDs(); len(nodes) > 0 && !_u.mutation.UsageLogsCleared() {
+		edge := &sqlgraph.EdgeSpec{
+			Rel:     sqlgraph.O2M,
+			Inverse: false,
+			Table:   user.UsageLogsTable,
+			Columns: []string{user.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.Clear = append(_spec.Edges.Clear, edge)
+	}
+	if nodes := _u.mutation.UsageLogsIDs(); len(nodes) > 0 {
+		edge := &sqlgraph.EdgeSpec{
+			Rel:     sqlgraph.O2M,
+			Inverse: false,
+			Table:   user.UsageLogsTable,
+			Columns: []string{user.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.Add = append(_spec.Edges.Add, edge)
+	}
 	if _node, err = sqlgraph.UpdateNodes(ctx, _u.driver, _spec); err != nil {
 		if _, ok := err.(*sqlgraph.NotFoundError); ok {
 			err = &NotFoundError{user.Label}
@@ -1012,6 +1094,21 @@ func (_u *UserUpdateOne) AddAllowedGroups(v ...*Group) *UserUpdateOne {
 	return _u.AddAllowedGroupIDs(ids...)
 }
 
+// AddUsageLogIDs adds the "usage_logs" edge to the UsageLog entity by IDs.
+func (_u *UserUpdateOne) AddUsageLogIDs(ids ...int64) *UserUpdateOne {
+	_u.mutation.AddUsageLogIDs(ids...)
+	return _u
+}
+
+// AddUsageLogs adds the "usage_logs" edges to the UsageLog entity.
+func (_u *UserUpdateOne) AddUsageLogs(v ...*UsageLog) *UserUpdateOne {
+	ids := make([]int64, len(v))
+	for i := range v {
+		ids[i] = v[i].ID
+	}
+	return _u.AddUsageLogIDs(ids...)
+}
+
 // Mutation returns the UserMutation object of the builder.
 func (_u *UserUpdateOne) Mutation() *UserMutation {
 	return _u.mutation
@@ -1122,6 +1219,27 @@ func (_u *UserUpdateOne) RemoveAllowedGroups(v ...*Group) *UserUpdateOne {
 	return _u.RemoveAllowedGroupIDs(ids...)
 }
 
+// ClearUsageLogs clears all "usage_logs" edges to the UsageLog entity.
+func (_u *UserUpdateOne) ClearUsageLogs() *UserUpdateOne {
+	_u.mutation.ClearUsageLogs()
+	return _u
+}
+
+// RemoveUsageLogIDs removes the "usage_logs" edge to UsageLog entities by IDs.
+func (_u *UserUpdateOne) RemoveUsageLogIDs(ids ...int64) *UserUpdateOne {
+	_u.mutation.RemoveUsageLogIDs(ids...)
+	return _u
+}
+
+// RemoveUsageLogs removes "usage_logs" edges to UsageLog entities.
+func (_u *UserUpdateOne) RemoveUsageLogs(v ...*UsageLog) *UserUpdateOne {
+	ids := make([]int64, len(v))
+	for i := range v {
+		ids[i] = v[i].ID
+	}
+	return _u.RemoveUsageLogIDs(ids...)
+}
+
 // Where appends a list predicates to the UserUpdate builder.
 func (_u *UserUpdateOne) Where(ps ...predicate.User) *UserUpdateOne {
 	_u.mutation.Where(ps...)
@@ -1520,6 +1638,51 @@ func (_u *UserUpdateOne) sqlSave(ctx context.Context) (_node *User, err error) {
 		edge.Target.Fields = specE.Fields
 		_spec.Edges.Add = append(_spec.Edges.Add, edge)
 	}
+	if _u.mutation.UsageLogsCleared() {
+		edge := &sqlgraph.EdgeSpec{
+			Rel:     sqlgraph.O2M,
+			Inverse: false,
+			Table:   user.UsageLogsTable,
+			Columns: []string{user.UsageLogsColumn},
+			Bidi:    false,
+			Target: &sqlgraph.EdgeTarget{
+				IDSpec: sqlgraph.NewFieldSpec(usagelog.FieldID, field.TypeInt64),
+			},
+		}
+		_spec.Edges.Clear = append(_spec.Edges.Clear, edge)
+	}
+	if nodes := _u.mutation.RemovedUsageLogsIDs(); len(nodes) > 0 && !_u.mutation.UsageLogsCleared() {
+		edge := &sqlgraph.EdgeSpec{
+			Rel:     sqlgraph.O2M,
+			Inverse: false,
+			Table:   user.UsageLogsTable,
+			Columns: []string{user.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.Clear = append(_spec.Edges.Clear, edge)
+	}
+	if nodes := _u.mutation.UsageLogsIDs(); len(nodes) > 0 {
+		edge := &sqlgraph.EdgeSpec{
+			Rel:     sqlgraph.O2M,
+			Inverse: false,
+			Table:   user.UsageLogsTable,
+			Columns: []string{user.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.Add = append(_spec.Edges.Add, edge)
+	}
 	_node = &User{config: _u.config}
 	_spec.Assign = _node.assignValues
 	_spec.ScanValues = _node.scanValues