#40 Issue 40: [Legal] PDF Generation for Vesting Agreements


Description:
When a vault is created, auto-generate a generic "Token Vesting Agreement" PDF mapping the on-chain variables (duration, cliff, amount) to a legal document.
Acceptance Criteria:

[ ] Create an HTML template.

[ ] Use Puppeteer or pdfkit to convert the template to PDF.

[ ] Return the PDF stream on GET /api/vault/:id/agreement.pdf.
Labels: legal, feature