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/edit-pdf.html

@@ -90,13 +90,13 @@
                         device.</p>
                 </div>
                 <input id="file-input" type="file" class="absolute top-0 left-0 w-full h-full opacity-0 cursor-pointer"
-                    accept="application/pdf">
+                    accept="application/pdf" multiple>
             </div>
 
             <div id="file-display-area" class="mt-4 space-y-2"></div>
 
-            <div id="embed-pdf-wrapper" class="hidden mt-6 w-full h-[75vh] border border-gray-600 rounded-lg">
-                <div id="embed-pdf-container" class="w-full h-full"></div>
+            <div id="embed-pdf-wrapper" class="hidden mt-6">
+                <div id="embed-pdf-container" class="w-full h-[75vh] border border-gray-600 rounded-lg"></div>
             </div>
 
         </div>