- Implement SQLite DDL writer to convert PostgreSQL schemas to SQLite-compatible SQL statements.
- Include automatic schema flattening, type mapping, auto-increment detection, and function translation.
- Add templates for creating tables, indexes, unique constraints, check constraints, and foreign keys.
- Implement tests for writer functionality and data type mapping.
* Introduce `--flatten-schema` flag to convert, merge, and split commands.
* Modify database writing functions to support flattened schema names.
* Update template functions to handle schema.table naming convention.
* Enhance PostgreSQL writer to utilize flattened schema in generated SQL.
* Update tests to ensure compatibility with new flattening feature.
* Dependencies updated for improved functionality.
