claude: fold in old sow-tools

internal/topdata/portraits_migrate.go

@@ -0,0 +1,8 @@
+package topdata
+
+func importLegacyPortraits(referenceBuilderDir, dataDir string, legacyTLK *legacyTLKData) (int, error) {
+	if legacyTLK == nil {
+		return 0, nil
+	}
+	return importLegacyDatasetMirror(referenceBuilderDir, dataDir, "portraits", "portraits.2da", nil)
+}