feat(loyalty): organization loyalty settings API

Adds GET and PUT /marketing/loyalty-settings and GET
/marketing/loyalty-settings/history (docs/prd-point-coin.md F2, PC-302).

The settings are the point value, the exchange rate, transfer limits and
the stored expiry settings. PUT merges the body like the outlet settings
and is limited to loyalty managers. Every response carries the impact of
the change on the balances in circulation: outstanding EnakPoint and
EnakCoin, their rupiah value, and the coins exchanged into points, before
and after. With ?dry_run=true nothing is saved and the response lists the
keys that would change, for the warning shown before saving.

Saving records each change in loyalty_setting_changes with who made it;
history can be filtered to one outlet. Changing the value leaves what was
already written alone. The diff behind saving and previewing is shared.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/service/loyalty_settings_service.go

@@ -24,14 +24,26 @@ type LoyaltySettingsService interface {
 	// UpdateOutletSettings applies a JSON body on top of the current settings: fields
 	// left out keep their value, and null clears an optional limit.
 	UpdateOutletSettings(ctx context.Context, apctx *appcontext.ContextInfo, outletID uuid.UUID, body []byte) *contract.Response
+
+	GetOrganizationSettings(ctx context.Context, apctx *appcontext.ContextInfo) *contract.Response
+	// UpdateOrganizationSettings applies a JSON body like UpdateOutletSettings. With
+	// dryRun it only validates and reports what would change and its impact.
+	UpdateOrganizationSettings(ctx context.Context, apctx *appcontext.ContextInfo, body []byte, dryRun bool) *contract.Response
+	// ListHistory returns the settings history of the organization, or of one outlet.
+	ListHistory(ctx context.Context, apctx *appcontext.ContextInfo, outletID *uuid.UUID, page, limit int) *contract.Response
+}
+
+type outstandingBalanceReader interface {
+	OrganizationOutstanding(ctx context.Context, organizationID uuid.UUID) (points, coins int64, err error)
 }
 
 type LoyaltySettingsServiceImpl struct {
-	settings *processor.LoyaltySettingsProcessor
+	settings    *processor.LoyaltySettingsProcessor
+	outstanding outstandingBalanceReader
 }
 
-func NewLoyaltySettingsService(settings *processor.LoyaltySettingsProcessor) *LoyaltySettingsServiceImpl {
-	return &LoyaltySettingsServiceImpl{settings: settings}
+func NewLoyaltySettingsService(settings *processor.LoyaltySettingsProcessor, outstanding outstandingBalanceReader) *LoyaltySettingsServiceImpl {
+	return &LoyaltySettingsServiceImpl{settings: settings, outstanding: outstanding}
 }
 
 func (s *LoyaltySettingsServiceImpl) GetOutletSettings(ctx context.Context, apctx *appcontext.ContextInfo, outletID uuid.UUID) *contract.Response {
@@ -115,3 +127,86 @@ func loyaltyErrorResponse(err error) *contract.Response {
 		contract.NewResponseError(code, constants.LoyaltySettingsServiceEntity, message),
 	})
 }
+
+func (s *LoyaltySettingsServiceImpl) GetOrganizationSettings(ctx context.Context, apctx *appcontext.ContextInfo) *contract.Response {
+	current, err := s.settings.Organization(ctx, apctx.OrganizationID)
+	if err != nil {
+		return loyaltyErrorResponse(err)
+	}
+	view, err := s.organizationView(ctx, apctx.OrganizationID, *current, *current, nil, false)
+	if err != nil {
+		return loyaltyErrorResponse(err)
+	}
+	return contract.BuildSuccessResponse(view)
+}
+
+// organizationSettingsInput is what PUT accepts: the settings plus the read-only fields
+// of the GET response, which are ignored.
+type organizationSettingsInput struct {
+	*models.OrganizationLoyaltySettings
+	Impact  json.RawMessage `json:"impact"`
+	Changes json.RawMessage `json:"changes"`
+	DryRun  json.RawMessage `json:"dry_run"`
+}
+
+func (s *LoyaltySettingsServiceImpl) UpdateOrganizationSettings(ctx context.Context, apctx *appcontext.ContextInfo, body []byte, dryRun bool) *contract.Response {
+	current, err := s.settings.Organization(ctx, apctx.OrganizationID)
+	if err != nil {
+		return loyaltyErrorResponse(err)
+	}
+	next := *current
+	decoder := json.NewDecoder(bytes.NewReader(body))
+	decoder.DisallowUnknownFields()
+	if err := decoder.Decode(&organizationSettingsInput{OrganizationLoyaltySettings: &next}); err != nil {
+		return contract.BuildErrorResponse([]*contract.ResponseError{
+			contract.NewResponseError(constants.MalformedFieldErrorCode, constants.LoyaltySettingsServiceEntity, fmt.Sprintf("invalid request body: %v", err)),
+		})
+	}
+
+	var changes []models.LoyaltySettingChange
+	if dryRun {
+		changes, err = s.settings.PreviewOrganization(ctx, apctx.OrganizationID, next)
+	} else {
+		changes, err = s.settings.UpdateOrganization(ctx, apctx.OrganizationID, apctx.UserID, next)
+	}
+	if err != nil {
+		return loyaltyErrorResponse(err)
+	}
+	after := next
+	if !dryRun {
+		saved, err := s.settings.Organization(ctx, apctx.OrganizationID)
+		if err != nil {
+			return loyaltyErrorResponse(err)
+		}
+		after = *saved
+	}
+	view, err := s.organizationView(ctx, apctx.OrganizationID, *current, after, changes, dryRun)
+	if err != nil {
+		return loyaltyErrorResponse(err)
+	}
+	return contract.BuildSuccessResponse(view)
+}
+
+func (s *LoyaltySettingsServiceImpl) ListHistory(ctx context.Context, apctx *appcontext.ContextInfo, outletID *uuid.UUID, page, limit int) *contract.Response {
+	history, err := s.settings.ListChanges(ctx, apctx.OrganizationID, outletID, page, limit)
+	if err != nil {
+		return loyaltyErrorResponse(err)
+	}
+	return contract.BuildSuccessResponse(history)
+}
+
+func (s *LoyaltySettingsServiceImpl) organizationView(ctx context.Context, organizationID uuid.UUID, before, after models.OrganizationLoyaltySettings, changes []models.LoyaltySettingChange, dryRun bool) (*models.OrganizationLoyaltySettingsView, error) {
+	points, coins, err := s.outstanding.OrganizationOutstanding(ctx, organizationID)
+	if err != nil {
+		return nil, err
+	}
+	if changes == nil {
+		changes = []models.LoyaltySettingChange{}
+	}
+	return &models.OrganizationLoyaltySettingsView{
+		OrganizationLoyaltySettings: after,
+		Impact:                      models.NewLoyaltySettingsImpact(points, coins, before, after),
+		Changes:                     changes,
+		DryRun:                      dryRun,
+	}, nil
+}