Add Feature to Export Verifiable Credentials to Branded PDF Reports

### Problem description
Guardian should support exporting Verifiable Credentials (VCs) for key project documents into PDF format. This feature will allow users to generate standardized, professionally formatted reports directly from Guardian, suitable for registry review, audits, and external sharing.
The export should support the following document types:
- Project Description (PD)
- Monitoring Report (MR)
- Validation Report
- Verification Report
Each PDF must be generated from the underlying VC data to ensure data integrity and traceability.
### Requirements
- Enable PDF export for each document type listed above
- PDFs must be generated directly from VC content (no manual data re-entry)
- Support customizable PDF templates per organization
- Templates should allow:
- Company branding (logo, colors, fonts)
- Standardized layout and section ordering
- Registry-specific formatting rules
**Example Use Case (Verra)**
Using Verra as a reference implementation:
- Verra can define a standardized PDF template aligned with their branding and reporting structure
- All Guardian-exported PDFs for Verra-related projects follow this approved format
- Ensures consistency between Guardian outputs and Verra’s expected documentation for PD, MR, Validation, and Verification

### Definition of done
- Users can export each supported document type as a PDF
- PDF content matches the VC data exactly
- Organization-specific templates can be configured and reused
- Multiple organizations can maintain independent PDF templates
- Exported PDFs are suitable for submission to registries and third-party reviewers. These PDFs will be shared outside of Guardian.

### Acceptance criteria
As mentioned in DOD