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

public/locales/en/tools.json

@@ -86,7 +86,10 @@
     },
     "addStamps": {
         "name": "Add Stamps",
-        "subtitle": "Add image stamps to your PDF using the annotation toolbar."
+        "subtitle": "Add image stamps to your PDF using the annotation toolbar.",
+        "usernameLabel": "Stamp Username",
+        "usernamePlaceholder": "Enter your name (for stamps)",
+        "usernameHint": "This name will appear on stamps you create."
     },
     "removeAnnotations": {
         "name": "Remove Annotations",