infra: add logging wrapping

Resolves issues with gcp cloud logging quirks such as field names

go/internal/billing/webhooks.go

@@ -4,9 +4,10 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"log/slog"
 	"time"
 
+	"github.com/flowy-live/llink/internal/utils/flog"
+
 	"github.com/stripe/stripe-go/v85"
 	"github.com/stripe/stripe-go/v85/webhook"
 )
@@ -17,7 +18,7 @@ func (s *serviceImpl) HandleWebhook(ctx context.Context, payload []byte, signatu
 		return fmt.Errorf("verify stripe signature: %w", err)
 	}
 
-	slog.Info("stripe webhook", "type", event.Type, "id", event.ID)
+	flog.Info("stripe webhook", "type", event.Type, "id", event.ID)
 
 	switch event.Type {
 	case "checkout.session.completed":