support truncate table

currently the only way to quickly clean the data of a table is drop the table then create a new one. perhaps we can support a "truncate table" command to let users to clean the table quickly.

No files or tests are identified in the issue. Start by locating the existing table drop and creation command paths, then determine how a truncate operation can clear table data while preserving the table. Done means users can invoke a truncate-table command without dropping and recreating the table, with behavior covered by relevant tests.

Written by the indexing model from the issue text.