Add new posterize feature that allows splitting PDF pages into a grid of smaller pages. The tool includes:
- Configurable rows and columns
- Page size and orientation options
- Content scaling modes
- Overlap settings for assembly
- Page range selection
refactor(form-filler): improve form field creation with DOM methods
refactor(compare-pdfs): use textContent instead of innerHTML
refactor(duplicate-organize): replace innerHTML with DOM methods
style(main): remove commented start app line
feat(config): add pdf-tools config file with tool categories