Upgrade UI of the Accounting page (Monthly accounting report)

🔍 Problem Statement

As a finance user, I experience a legacy Bootstrap Monthly accounting report page, which results in a jarring transition from the surrounding Preline dashboard.

💡 User Story

1. As a finance user, I want the Monthly accounting report page upgraded to Preline, so that month-end reconciliation happens in the same interface as the rest of the dashboard.

2. As a finance user, I want the ledger table to stay readable across horizontal scroll, so that I can trace a transaction row across all seven ledger accounts.

🎯 Definition of Done

A feature is done when:

1. Given a finance user opens Accounting, when they select a month and currency, then the ledger table renders on Preline with all rows and both column groups intact.

2. Balance Sheet: Cash - Offline payments, Cash - Online payments, Customer balance, Account receivable, Deferred revenue, Taxes

3. Profit & Loss: Recognized revenue

4. Summary rows: Opening Balance, Total, Closing Balance, Net Agency

5. Given the ledger table is scrolled horizontally, when the user traces a row, then the row-label column stays sticky and both group headers stay aligned to their columns.

6. Given the export controls, when triggered, then per-row download icons, the AR and DR totals-column exports, the total export, and both ALPHA header exports return the same files as today.

7. This change will impact the UI only (the Accounting page Blade view and the Preline AccountingController JS controller); no API, SDK, or Integration changes expected.