fix: order platform saga query by version for deterministic migration

loadPlatformSagas queries all platform_saga_definition rows and stores
them in a map keyed by name. When multiple versions exist (e.g.,
stripe_payment v1/v2/v3), the last row scanned overwrites the entry.
Without ORDER BY version, the winning version was non-deterministic,
causing migration tests to fail when an older version won and the
similarity check against the tenant's latest-version script dropped
below threshold (69% vs required 95%).

Author: bjcoombs

services/reference-data/saga/override_api.go

@@ -412,7 +412,7 @@ func (s *OverrideService) loadPlatformSagas(ctx context.Context) (map[string]Pla
 	rows, err := s.pool.Query(ctx, `
 		SELECT id, name, version, script, display_name, description
 		FROM public.platform_saga_definition
-		ORDER BY name`)
+		ORDER BY name, version`)
 	if err != nil {
 		return nil, fmt.Errorf("query platform sagas: %w", err)
 	}