Frontend: Transaction history page with CSV export

[KuchiMercy]

Summary

Users have no consolidated view of their fund movements across all escrows. A transaction history page is needed for record-keeping, reconciliation, and tax reporting.

Requirements

• Build a /transactions page showing all fund movements for the authenticated user
• Transaction types: deposits (funding), milestone releases, refunds (expiration/cancellation), platform fees
• Each row shows: date, type, escrow title (linked), amount, asset, counterparty address, Stellar transaction hash (linked to explorer)
• Filter by: transaction type, date range, amount range
• Sort by: date (newest/oldest), amount
• CSV export button that downloads the filtered results
• Pagination (20 per page) or infinite scroll

Acceptance Criteria

• Transaction history page shows all fund movements for the current user
• Each transaction links to the relevant escrow detail page
• Stellar transaction hashes link to the appropriate network explorer (testnet/mainnet)
• Filters work correctly and update the displayed results
• CSV export includes all columns and respects active filters
• Empty state for users with no transactions
• Loading skeleton while data is being fetched

Context

• Escrow events contain fund movement data: apps/backend/src/modules/escrow/entities/escrow-event.entity.ts
• Stellar event records: apps/backend/src/modules/stellar/entities/stellar-event.entity.ts
• A new backend endpoint may be needed to aggregate transactions across escrows

Points: 150