### CHANGES
- Add `.browserslistrc` to define target browser versions.
- Upgrade `pdfjs-dist` dependency from v2.16 to v4.2.67.
- Upgrade `nanoid` dependency from v4.0.2 to v5.0.9.
- Introduce `pdf-config.ts` for centralized PDF.js worker setup.
- Refactor `PdfConversionService` to use new PDF worker configuration.
- Add static `pdf.worker.min.mjs` to serve PDF.js worker.
- Update Vite configuration for ESNext build target and PDF.js.