fix(eventstore): use decimal, correct mirror (#9914)

# 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

---------

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

internal/query/user_grant.go

@@ -280,7 +280,7 @@ func (q *Queries) UserGrants(ctx context.Context, queries *UserGrantsQueries, sh
 		return nil, zerrors.ThrowInternal(err, "QUERY-wXnQR", "Errors.Query.SQLStatement")
 	}
 
-	latestSequence, err := q.latestState(ctx, userGrantTable)
+	latestState, err := q.latestState(ctx, userGrantTable)
 	if err != nil {
 		return nil, err
 	}
@@ -293,7 +293,7 @@ func (q *Queries) UserGrants(ctx context.Context, queries *UserGrantsQueries, sh
 		return nil, err
 	}
 
-	grants.State = latestSequence
+	grants.State = latestState
 	return grants, nil
 }