feat: Add VitePress docs, EPUB to PDF tool, Phosphor icons, and licensing updates

- Set up VitePress documentation site (docs:dev, docs:build, docs:preview)
- Added Getting Started, Tools Reference, Contributing, and Commercial License pages
- Created self-hosting guides for Docker, Vercel, Netlify, Cloudflare, AWS, Hostinger, Nginx, Apache
- Updated README with documentation link, sponsors section, and docs contribution guide

- Added EPUB to PDF converter using LibreOffice WASM

- Migrated to Phosphor Icons for consistent iconography

- Added donation ribbon banner on landing page
- Removed 'Like My Work?' section (replaced by ribbon)
- Updated licensing.html with delivery model, AGPL notice, invoicing, and no-refund policy

- Added Commercial License documentation page
- Updated translations table (Chinese added, marked non-English as In Progress)

- Added sponsors.yml workflow for auto-generating sponsor avatars

src/pages/divide-pages.html

@@ -100,10 +100,20 @@
                     <ul class="list-disc list-inside text-xs text-gray-400 mt-1 space-y-1">
                         <li><strong>Vertical:</strong> Split each page into left and right halves.</li>
                         <li><strong>Horizontal:</strong> Split each page into top and bottom halves.</li>
-                        <li>The result will have twice as many pages as the original.</li>
+                        <li>Specify which pages to divide. Other pages will be kept as-is.</li>
+                        <li>Leave blank or use "all" to divide all pages.</li>
                     </ul>
                 </div>
 
+                <div class="mb-4">
+                    <label for="page-range" class="block mb-2 text-sm font-medium text-gray-300">Pages to Divide</label>
+                    <input type="text" id="page-range"
+                        class="bg-gray-700 border border-gray-600 text-white text-sm rounded-lg focus:ring-indigo-500 focus:border-indigo-500 block w-full p-2.5"
+                        placeholder="e.g. 1-5, 8, 11-13 (leave blank for all pages)">
+                    <p class="mt-1 text-xs text-gray-400">Enter page numbers separated by commas or ranges with hyphens.
+                    </p>
+                </div>
+
                 <div class="mb-4">
                     <label for="split-type" class="block mb-2 text-sm font-medium text-gray-300">Split Direction</label>
                     <select id="split-type"