fix(drizzle-kit): include ON DELETE/ON UPDATE in SQLite ALTER TABLE ADD COLUMN

[JosephDoUrden]

Summary

Fix SQLiteAlterTableAddColumnConvertor omitting ON DELETE and ON UPDATE clauses from REFERENCES in ALTER TABLE ADD COLUMN statements.

Fixes #5619

Problem

When using drizzle-kit generate with SQLite, foreign key columns added via ALTER TABLE ADD COLUMN lost their referential actions:

-- Generated (missing ON DELETE SET NULL)
ALTER TABLE `tasks` ADD `assigned_to` text REFERENCES users(id);

-- Expected
ALTER TABLE `tasks` ADD `assigned_to` text REFERENCES users(id) ON DELETE SET NULL;

SQLiteSquasher.unsquashFK() correctly parsed onDelete/onUpdate, but the referenceStatement template in SQLiteAlterTableAddColumnConvertor.convert() only output REFERENCES table(col) without the action clauses.

Fix

Append ON DELETE and ON UPDATE clauses to the referenceStatement when present, matching the pattern used by SQLiteCreateTableConvertor.

Test plan

• Existing SQLite tests pass (tests/test/sqlite.test.ts)
• LibSQL statement combiner tests pass (tests/statements-combiner/libsql-statements-combiner.test.ts)