Implement center-point based bbox scaling with directional compensation
to capture field labels that typically appear above or to the left of
field values. This improves YOLO training data quality by including
contextual information around field values.
Key changes:
- Add shared.bbox module with ScaleStrategy dataclass and expand_bbox function
- Define field-specific strategies (ocr_number, bankgiro, invoice_date, etc.)
- Support manual_mode for minimal padding (no scaling)
- Integrate expand_bbox into AnnotationGenerator
- Add FIELD_TO_CLASS mapping for field_name to class_name lookup
- Comprehensive tests with 100% coverage (45 tests)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Add validation that checks PDF files start with '%PDF' magic bytes
before accepting uploads. This prevents attackers from uploading
malicious files (executables, scripts) by renaming them to .pdf.
- Add validate_pdf_magic_bytes() function with clear error messages
- Integrate validation in upload_document endpoint after file read
- Add comprehensive test coverage (13 test cases)
Addresses medium-risk security issue from code review.
