feat(pdf): add PDF processing capabilities

Add new PDF processing module with the following features:
- PDF text extraction and formatting to HTML/Markdown
- Image extraction with multiple format support (JPEG, PNG, TIFF)
- Link extraction from PDF documents
- Metadata extraction including title, author, dates
- Support for both local and remote PDF files

Also includes:
- New configuration options for HTML attribute handling
- Internal/external link filtering improvements
- Version bump to 0.4.300b4

crawl4ai/models.py

@@ -143,6 +143,7 @@ class AsyncCrawlResponse(BaseModel):
 ###############################
 class MediaItem(BaseModel):
     src: Optional[str] = ""
+    data: Optional[str] = ""
     alt: Optional[str] = ""
     desc: Optional[str] = ""
     score: Optional[int] = 0