Integrate session management, multilingual IPC handlers, and Book database operations

- Add `LocalSystem` with handlers for session retrieval (`userId`, `lang`) and error handling.
- Extend IPC handlers to support multilingual operations (`fr`, `en`) and session data injection

electron/database/System.ts

@@ -0,0 +1,66 @@
+import { getDatabaseService } from './database.service.js';
+import { encryptDataWithUserKey, decryptDataWithUserKey, hashElement } from './encryption.js';
+import type { Database } from 'node-sqlite3-wasm';
+import crypto from 'crypto';
+
+export default class System {
+    public static getDb(): Database {
+        const db: Database | null = getDatabaseService().getDb();
+        if (!db) {
+            throw new Error('Database not initialized');
+        }
+        return db;
+    }
+    
+    public static encryptDataWithUserKey(data: string, userKey: string): string {
+        return encryptDataWithUserKey(data, userKey);
+    }
+    
+    public static decryptDataWithUserKey(encryptedData: string, userKey: string): string {
+        return decryptDataWithUserKey(encryptedData, userKey);
+    }
+    
+    public static createUniqueId(): string {
+        return crypto.randomUUID();
+    }
+    
+    static htmlToText(htmlNode: string): string {
+        let text: string = htmlNode
+            .replace(/<\/?p[^>]*>/gi, '\n')
+            .replace(/<br\s*\/?>/gi, '\n')
+            .replace(/<\/?(span|h[1-6])[^>]*>/gi, '');
+        text = text
+            .replace(/&apos;/g, "'")
+            .replace(/&quot;/g, '"')
+            .replace(/&amp;/g, '&')
+            .replace(/&lt;/g, '<')
+            .replace(/&gt;/g, '>')
+            .replace(/&#39;/g, "'");
+        text = text.replace(/\r?\n\s*\n/g, '\n');
+        text = text.replace(/[ \t]+/g, ' ');
+        
+        return text.trim();
+    }
+    
+    public static getCurrentDate(): string {
+        return new Date().toISOString();
+    }
+    
+    static dateToMySqlDate(isoDateString: string): string {
+        const dateObject: Date = new Date(isoDateString);
+        
+        function padWithZeroes(value: number): string {
+            return value.toString().padStart(2, '0');
+        }
+        
+        const year: number = dateObject.getFullYear();
+        const month: string = padWithZeroes(dateObject.getMonth() + 1);
+        const day: string = padWithZeroes(dateObject.getDate());
+        
+        return `${year}-${month}-${day}`;
+    }
+    
+    public static hashElement(element: string): string {
+        return hashElement(element);
+    }
+}