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/database.service.ts

@@ -1,7 +1,7 @@
 import sqlite3 from 'node-sqlite3-wasm';
 import path from 'path';
 import { app } from 'electron';
-import { initializeSchema } from './schema.js';
+import { initializeSchema, runMigrations } from './schema.js';
 
 // Type alias for compatibility
 export type Database = sqlite3.Database;
@@ -36,9 +36,12 @@ export class DatabaseService {
         this.userEncryptionKey = encryptionKey;
         this.userId = userId;
 
-        // Initialize schema
+        // Initialize schema (creates tables if they don't exist)
         initializeSchema(this.db);
 
+        // Run migrations (updates existing tables if needed)
+        runMigrations(this.db);
+
         console.log(`Database initialized for user ${userId} at ${dbPath}`);
     }