Add PDF Generation to Lovable App

Add PDF generation and export functionality to my Lovable app.

REQUIREMENTS:
1. Install and configure a client-side PDF library (jsPDF with html2canvas, or @react-pdf/renderer).
2. Create a branded invoice PDF template with: company logo, invoice number, date, bill-to info, line items table (description, quantity, rate, amount), subtotal, tax, total, payment terms, and footer with company info.
3. Create a report PDF template with: title, date range, summary metrics, data table, and charts rendered as images.
4. Add a "Download PDF" button on invoice and report pages that generates and downloads the PDF.
5. Add a "Preview" button that opens the PDF in a new browser tab before downloading.
6. Support dynamic data — pull invoice or report data from Supabase and populate the template.
7. Format currency, dates, and numbers properly in the PDF.
8. Add batch export: select multiple records and generate a combined PDF or ZIP of individual PDFs.

DATABASE:
- No new tables. Uses existing invoice/report data.
- Optionally log PDF downloads in an "export_logs" table.

SECURITY:
- Generate PDFs client-side to avoid server load.
- Ensure users can only export their own data (respect RLS).