ci: Improve Docker build workflow and update dependencies

- Add release type detection to distinguish between version tags and edge builds
- Implement separate Docker build steps for release and edge builds with appropriate tags
- Add edge and SHA-based image tags for main branch builds
- Update nginx configuration to support Vietnamese (vi) language routing
- Simplify nginx location block to handle static files and fallback to index.html
- Remove javascript-obfuscator and ts-migrate from dependencies
- Update README with simplified self-hosting instructions using npx http-server
- Consolidate multiple server setup examples into single recommended approach
- Update build preview command to use npm run preview instead of npx serve
- Improve localization files for German, English, Vietnamese, and Chinese
- Update worker files and TypeScript logic files for improved functionality
- Enhance PDF tool pages with better structure and internationalization support

src/pages/add-stamps.html

@@ -79,6 +79,16 @@
         Upload a PDF, add image stamps using the toolbar, and then save the stamped PDF.
       </p>
 
+      <div class="mb-4">
+        <label for="stamp-username" class="block text-sm font-medium text-gray-300 mb-2"
+          data-i18n="tools:addStamps.usernameLabel">Stamp Username</label>
+        <input type="text" id="stamp-username"
+          class="w-full px-4 py-2 bg-gray-900 border border-gray-600 rounded-lg text-white placeholder-gray-400 focus:outline-none focus:ring-2 focus:ring-indigo-500 focus:border-transparent"
+          placeholder="Enter your name (for stamps)" data-i18n-placeholder="tools:addStamps.usernamePlaceholder" />
+        <p class="text-xs text-gray-500 mt-1" data-i18n="tools:addStamps.usernameHint">This name will appear on stamps
+          you create.</p>
+      </div>
+
       <div id="drop-zone"
         class="relative flex flex-col items-center justify-center w-full h-48 md:h-64 border-2 border-dashed border-gray-600 rounded-xl cursor-pointer bg-gray-900 hover:bg-gray-700 transition-colors duration-300">
         <div class="flex flex-col items-center justify-center pt-5 pb-6">