`MODIFY STRUCTURE` — alter an existing table

[DDecoene]

There is currently no way to add, rename, or drop a column on an existing table except DROP TABLE + CREATE TABLE. dBASE III had MODIFY STRUCTURE (full-screen editor).

Proposal: implement it as an Assistant wizard (src/ui/wizards/) showing the current schema in an editable grid, generating ALTER TABLE statements through ServerDatabaseBridge. SQLite supports ADD COLUMN, RENAME COLUMN, and DROP COLUMN natively (3.35+); type changes need a copy-table dance.

A plain-command fallback like ALTER TABLE <name> ADD <col> <type> would also be welcome as a first step.

[DDecoene]

Already implemented and shipped in PR #16 (commit 4c31536, "MODIFY STRUCTURE / ALTER TABLE"). MODIFY STRUCTURE plus the ALTER TABLE ADD/DROP/RENAME/ALTER command family and the ModStructWizard are all in main. Closing as done — was left open by oversight.