fix: preserve legacy time casts throughout index migrations

internal/data/business/query_indexes.go

@@ -74,7 +74,17 @@ func migrateQueryIndexes(db *gorm.DB, indexes []businessQueryIndex) error {
 		}
 		// 同一大表的多个索引合并构建，减少重复扫描。
 		if len(additions) > 0 {
-			if err := db.Exec("ALTER TABLE `" + table + "` " + strings.Join(additions, ",") + ", ALGORITHM=INPLACE, LOCK=NONE").Error; err != nil {
+			build := func(conn *gorm.DB) error {
+				return conn.Exec("ALTER TABLE `" + table + "` " + strings.Join(additions, ",") + ", ALGORITHM=INPLACE, LOCK=NONE").Error
+			}
+			// Later indexes also evaluate the historical generated time column.
+			// Apply the same connection-local compatibility rule as its first index.
+			if table == "tab_user" && db.Migrator().HasColumn(table, "sw_register_time_unix") {
+				err = withLegacyRegistrationCast(db, build)
+			} else {
+				err = build(db)
+			}
+			if err != nil {
 				return fmt.Errorf("add query indexes on %s: %w", table, err)
 			}
 		}