Upgrade database schema to version 2 and remove unused meta_* columns

- 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.

electron/database/models/Book.ts

@@ -844,8 +844,6 @@ export default class Book {
         const decryptedChapters: any[] = [];
 
         for (const chapter of chapters) {
-            if (!chapter.meta_chapter) continue;
-            if (!chapter.meta_chapter_content) continue;
             decryptedChapters.push({
                 id: '',
                 title: chapter.title ? System.decryptDataWithUserKey(chapter.title, userKey) : '',