fix(eventstore): use decimal, correct mirror (#9916)

# Eventstore fixes

- `event.Position` used float64 before which can lead to [precision
loss](https://github.com/golang/go/issues/47300). The type got replaced
by [a type without precision
loss](https://github.com/jackc/pgx-shopspring-decimal)
- the handler reported the wrong error if the current state was updated
and therefore took longer to retry failed events.

# Mirror fixes

- max age of auth requests can be configured to speed up copying data
from `auth.auth_requests` table. Auth requests last updated before the
set age will be ignored. Default is 1 month
- notification projections are skipped because notifications should be
sent by the source system. The projections are set to the latest
position
- ensure that mirror can be executed multiple times

internal/v2/eventstore/event_store.go

@@ -2,6 +2,8 @@ package eventstore
 
 import (
 	"context"
+
+	"github.com/shopspring/decimal"
 )
 
 func NewEventstore(querier Querier, pusher Pusher) *EventStore {
@@ -30,12 +32,12 @@ type healthier interface {
 }
 
 type GlobalPosition struct {
-	Position        float64
+	Position        decimal.Decimal
 	InPositionOrder uint32
 }
 
 func (gp GlobalPosition) IsLess(other GlobalPosition) bool {
-	return gp.Position < other.Position || (gp.Position == other.Position && gp.InPositionOrder < other.InPositionOrder)
+	return gp.Position.LessThan(other.Position) || (gp.Position.Equal(other.Position) && gp.InPositionOrder < other.InPositionOrder)
 }
 
 type Reducer interface {