feat: add "Add Page Labels" tool to the application

- Introduced a new tool for adding page labels to PDF documents, allowing users to apply Roman numerals, prefixes, and custom numbering ranges.
- Created a new HTML page for the tool with a user-friendly interface for file upload and label rule configuration.
- Implemented logic for handling file uploads, processing PDF files, and applying page labels based on user-defined rules.
- Added necessary types and utility functions for managing page label styles and normalization of start values.
- Updated main application configuration to include the new tool in the navigation.
- Added tests for page label utilities to ensure correct functionality.

vite.config.ts

@@ -410,6 +410,10 @@ export default defineConfig(() => {
           'delete-pages': resolve(__dirname, 'src/pages/delete-pages.html'),
           'organize-pdf': resolve(__dirname, 'src/pages/organize-pdf.html'),
           'page-numbers': resolve(__dirname, 'src/pages/page-numbers.html'),
+          'add-page-labels': resolve(
+            __dirname,
+            'src/pages/add-page-labels.html'
+          ),
           'add-watermark': resolve(__dirname, 'src/pages/add-watermark.html'),
           'header-footer': resolve(__dirname, 'src/pages/header-footer.html'),
           'invert-colors': resolve(__dirname, 'src/pages/invert-colors.html'),