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

docs/self-hosting/vercel.md

@@ -0,0 +1,75 @@
+# Deploy to Vercel
+
+[Vercel](https://vercel.com) offers the easiest deployment experience for static sites.
+
+## One-Click Deploy
+
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/clone?repository-url=https://github.com/bentopdf/bentopdf)
+
+## Manual Deployment
+
+### Step 1: Fork the Repository
+
+Fork [bentopdf/bentopdf](https://github.com/bentopdf/bentopdf) to your GitHub account.
+
+### Step 2: Import to Vercel
+
+1. Go to [vercel.com/new](https://vercel.com/new)
+2. Select your forked repository
+3. Configure the project:
+
+| Setting | Value |
+|---------|-------|
+| Framework Preset | Vite |
+| Build Command | `npm run build` |
+| Output Directory | `dist` |
+| Install Command | `npm install` |
+
+### Step 3: Environment Variables (Optional)
+
+Add these if needed:
+
+```
+SIMPLE_MODE=false
+```
+
+### Step 4: Deploy
+
+Click "Deploy" and wait for the build to complete.
+
+## Custom Domain
+
+1. Go to your project settings
+2. Navigate to "Domains"
+3. Add your custom domain
+4. Configure DNS as instructed
+
+## Limitations
+
+::: warning Large Files
+Vercel's serverless functions have a 50MB limit. Since BentoPDF is a static site, this shouldn't affect you, but WASM modules are large (~100MB total). Ensure they're served from the `/public` folder.
+:::
+
+## Troubleshooting
+
+### Build Timeout
+
+If builds timeout, try:
+
+```json
+// vercel.json
+{
+  "buildCommand": "npm run build",
+  "outputDirectory": "dist"
+}
+```
+
+### 404 on Refresh
+
+Add a `vercel.json` for SPA routing:
+
+```json
+{
+  "rewrites": [{ "source": "/(.*)", "destination": "/index.html" }]
+}
+```