Update backend API configuration and schema for improved functionality

- Modified TypeScript configuration to disable strict mode and allow importing TypeScript extensions.
- Updated Prisma schema to enhance the User model with a new debtAccounts field and refined asset/liability types.
- Adjusted environment variable parsing for PORT to use coercion for better type handling.
- Refactored various controllers and repositories to utilize type imports for better clarity and maintainability.
- Enhanced service layers with new methods for retrieving assets by type and calculating invoice statistics.
- Introduced new types for invoice statuses and asset types to ensure consistency across the application.

backend-api/src/repositories/LiabilityRepository.ts

@@ -1,6 +1,5 @@
-import {Liability, Prisma} from '@prisma/client';
+import type {Liability, Prisma} from '@prisma/client';
 import {DatabaseConnection} from '../config/database';
-import {IUserScopedRepository} from './interfaces/IRepository';
 
 const prisma = DatabaseConnection.getInstance();
 
@@ -8,13 +7,19 @@ const prisma = DatabaseConnection.getInstance();
  * Repository for Liability data access
  * Implements Single Responsibility Principle - handles only database operations
  */
-export class LiabilityRepository implements IUserScopedRepository<Liability> {
+export class LiabilityRepository {
   async findById(id: string): Promise<Liability | null> {
     return prisma.liability.findUnique({
       where: {id},
     });
   }
 
+  async findByIdAndUser(id: string, userId: string): Promise<Liability | null> {
+    return prisma.liability.findFirst({
+      where: {id, userId},
+    });
+  }
+
   async findAllByUser(userId: string): Promise<Liability[]> {
     return prisma.liability.findMany({
       where: {userId},
@@ -48,11 +53,11 @@ export class LiabilityRepository implements IUserScopedRepository<Liability> {
     const result = await prisma.liability.aggregate({
       where: {userId},
       _sum: {
-        currentBalance: true,
+        balance: true,
       },
     });
 
-    return result._sum.currentBalance || 0;
+    return result._sum.balance || 0;
   }
 
   /**