feat: support multiple PDF in PDF encryption tool

src/pages/decrypt-pdf.html

@@ -141,6 +141,12 @@
               >
               <span data-i18n="upload.orDragAndDrop">or drag and drop</span>
             </p>
+            <p
+              class="text-xs text-gray-500"
+              data-i18n="upload.hints.singleOrMultiplePdfs"
+            >
+              Single or multiple PDF files supported
+            </p>
             <p class="text-xs text-gray-500" data-i18n="upload.filesNeverLeave">
               Your files never leave your device.
             </p>
@@ -150,9 +156,28 @@
             type="file"
             class="absolute top-0 left-0 w-full h-full opacity-0 cursor-pointer"
             accept="application/pdf"
+            multiple
           />
         </div>
 
+        <!-- Control buttons for multi-file uploads -->
+        <div id="file-controls" class="hidden mt-4 flex gap-3">
+          <button
+            id="add-more-btn"
+            class="btn bg-indigo-600 hover:bg-indigo-700 text-white font-semibold px-4 py-2 rounded-lg flex items-center gap-2"
+          >
+            <i data-lucide="plus"></i>
+            <span data-i18n="upload.addMore">Add More Files</span>
+          </button>
+          <button
+            id="clear-files-btn"
+            class="btn bg-gray-600 hover:bg-gray-500 text-white font-semibold px-4 py-2 rounded-lg flex items-center gap-2"
+          >
+            <i data-lucide="trash-2"></i>
+            <span data-i18n="upload.clearAll">Clear All</span>
+          </button>
+        </div>
+
         <div id="file-display-area" class="mt-4 space-y-2"></div>
 
         <div id="tool-options" class="hidden mt-6 space-y-4">