Add localization to "download" button

src/pages/pdf-to-webp.html

@@ -186,8 +186,12 @@
             </p>
           </div>
 
-          <button id="process-btn" class="btn-gradient w-full">
-            Download All
+          <button
+            id="process-btn"
+            class="btn-gradient w-full"
+            data-i18n="common.convert"
+          >
+            Convert
           </button>
         </div>
       </div>