- Increment `SCHEMA_VERSION` to 2 in `schema.ts`.
- Remove all `meta_*` columns from database tables.
- Add migration logic to handle schema upgrades and clean up unused columns.
- Modify database models and repository methods to exclude `meta_*` fields for stricter typings and improved structure.
- Refactor and optimize query statements across repositories to align with new schema changes.
- Implement `schema.ts` for SQLite schema creation, indexing, and sync metadata initialization.
- Develop `encryption.ts` with AES-256-GCM encryption utilities for securing database data.
- Add `database.service.ts` to manage CRUD operations with encryption support, user-specific databases, and schema initialization.
- Integrate book, chapter, and character operations with encrypted content handling and sync preparation.
