Add bulk stream export to PDF for accounting and tax reporting

[Chuks-coderr]

Overview

Users need to provide stream payment history to accountants or tax preparers. A PDF export of all streams for a period would provide a structured, shareable summary.

Problem

The CSV export covers stream metadata but produces a machine-readable format unsuitable for direct sharing with accountants. A formatted PDF is needed for human-readable reporting.

Proposed Solution

• Add a "Export PDF" button in the dashboard export menu
• PDF includes: wallet address, date range, table of all streams with amounts, dates, and status, and a summary total
• Generated client-side using a PDF library to avoid server-side data processing

Acceptance Criteria

• PDF export button in the dashboard export menu
• PDF includes all streams for the selected date range
• Summary totals (total sent, total received) included
• Generated client-side with no data sent to a server
• Filename includes the wallet address and date range