Closes #20 Implement Comprehensive Transaction History and Ledger System

[Ndifreke000]

Brief Description of Actions Taken and Issues Faced

Actions Taken

• File Creation and Updates: Created nine files (configuration.ts, data-source.ts, transaction.entity.ts, ledger-entry.entity.ts, audit-log.entity.ts, account.entity.ts, transaction.service.ts, transaction.controller.ts, and the migrations/ directory) and updated treasury.module.ts to define entities, services, controllers, and TypeORM configuration for the Treasury module. These files implement a double-entry bookkeeping system with transaction management, audit logging, reconciliation, and reporting.
• Local PostgreSQL Setup: Installed PostgreSQL locally in the Codespace environment, started the service, configured the postgres user with a password (password), and created a budgetchain database to match src/config/configuration.ts. This enabled TypeORM to connect to a local database.
• Dependency Installation: Installed Node.js dependencies (typeorm, pg, @nestjs/typeorm, @nestjs/config, ts-node, typeorm-ts-node-commonjs) and PostgreSQL packages (postgresql, postgresql-contrib) to support the application and database.
• package.json Configuration: Added TypeORM scripts (typeorm, typeorm:migration:generate, typeorm:migration:run) to package.json to enable migration generation and execution.
• Database Configuration: Updated src/config/configuration.ts to define explicit database credentials (host: 'localhost', port: 5432, user: 'postgres', password: 'password', name: 'budgetchain') and ensured src/config/data-source.ts correctly accessed these for TypeORM migrations.
• Testing Instructions: Provided commands to generate and run migrations, start the NestJS application, and test API endpoints (POST /transactions, GET /transactions, POST /transactions/reconcile, GET /transactions/report) with curl.

Issues Faced with the Database

• No Database Configured: The initial error (ECONNREFUSED on localhost:5432) occurred because no PostgreSQL server was running locally, preventing TypeORM from connecting. This was evident from repeated connection failures in the logs.
• Configuration Mismatch: Earlier versions of data-source.ts had incorrect ConfigService usage (e.g., configService.get('database.host') instead of configService.get('database').host), causing TypeScript errors due to mismatched types and unrecognized nested keys.
• Missing PostgreSQL Installation: The Codespace environment lacked a PostgreSQL server, requiring manual installation and configuration of the database service, user, and database.
• Authentication Setup: The default postgres user needed a password to match the application’s configuration, and a specific database (budgetchain) had to be created to align with configuration.ts.

closes #20

[anonfedora]

Please, fix conflicts