FileHandlerTest:
  ✓ Constructor with default parameters
  ✓ Constructor with custom parameters
  ✓ validateFile accepts valid file
  ✓ validateFile rejects file too large
  ✓ validateFile rejects invalid file type
  ✓ getFileInfo returns complete file information
  ✓ convertToImages handles image file without conversion
  ✓ convertToImages detects MIME type from content
  ✓ PDF conversion succeeds for single-page PDF
  ✓ Single-page PDF returns exactly 1 image
  ✓ Single-page PDF reports correct page_count
  ✓ PDF conversion succeeds for multi-page PDF
  ✓ Multi-page PDF returns separate image for each page (3 images)
  ✓ Multi-page PDF reports correct page_count (3)
  ✓ Each page produces a valid image blob (not empty)
  ✓ Each page produces a DIFFERENT image (pages not combined/duplicated)
  ✓ Each converted image is a SINGLE page (not multi-page combined)