fix(eventstore): use decimal, correct mirror (#9906)

back port #9812, #9878, #9881, #9884

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

internal/eventstore/repository/mock/repository.mock.impl.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/shopspring/decimal"
 	"github.com/stretchr/testify/assert"
 	"go.uber.org/mock/gomock"
 
@@ -197,8 +198,8 @@ func (e *mockEvent) Sequence() uint64 {
 	return e.sequence
 }
 
-func (e *mockEvent) Position() float64 {
-	return 0
+func (e *mockEvent) Position() decimal.Decimal {
+	return decimal.Decimal{}
 }
 
 func (e *mockEvent) CreatedAt() time.Time {