feat: Add PDF document support

[chindris-mihai-alexandru]

Summary

Add support for sending PDF documents to models that support document analysis.

Current State

Model modalities include pdf but actual PDF handling is not implemented.

Proposed Implementation

1. PDF input handling

// File path
{ type: 'file', path: '/path/to/document.pdf', mimeType: 'application/pdf' }

// Base64 encoded
{ type: 'file', data: 'base64...', mimeType: 'application/pdf' }

// URL
{ type: 'file', url: 'https://example.com/doc.pdf' }

2. Models with PDF support

• Claude models (native PDF support)
• Gemini models (document understanding)

3. Fallback for non-PDF models

• Extract text from PDF using a library
• Send as text content instead

Technical Notes

• May need to add pdf-parse or similar dependency
• Consider file size limits
• Handle multi-page documents

Priority: Low

[chindris-mihai-alexandru]

Consolidated into #48 to keep roadmap tracking in one place.

[chindris-mihai-alexandru]

Reopening to track this item as a standalone issue while also keeping #48 as the roadmap index.

[chindris-mihai-alexandru]

Implemented: PDF/document input support via puter_path file parts + puter-chat file_path arg and docs. See commit fbb2428.