feat: Add optional public upload folder naming

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

frontend/index.html

@@ -45,6 +45,8 @@
       </div>
 
       <div class="mt-4 text-sm text-gray-500 dark:text-gray-400">
+        <label for="publicFolderName" class="font-medium">Optional folder name:</label>
+        <input type="text" id="publicFolderName" name="publicFolderName" maxlength="64" placeholder="e.g., Soccer game" class="mt-1 mx-auto block w-full max-w-sm rounded-lg border border-gray-300 bg-gray-50 p-2 text-sm text-gray-900 focus:border-blue-500 focus:ring-blue-500 dark:border-gray-600 dark:bg-gray-700 dark:text-white dark:placeholder-gray-400 dark:focus:border-blue-500 dark:focus:ring-blue-500">
       </div>
     </section>