feat: Implement API Pagination for Assets and Transactions

[ogazboiz]

Overview

This pull request implements a flexible and reusable pagination system for the kor-AssetForge backend API.

Key Changes

• Pagination Utility: Created a reusable Paginate helper in backend/utils/pagination.go.
• Asset List Pagination: Updated GET /api/v1/assets to support page and limit query parameters.
• Transaction List Endpoint: Implemented GET /api/v1/transactions with full pagination and optional filtering by asset_id.

Closes #30

[parkerwinner]

fix conflicts