refactor(ui): standardize button types and migrate file operations to V3 Action API

src/routes/events/[event_id]/+page.svelte

@@ -278,8 +278,7 @@
     <header class="ae_module_header">
         <span class="flex flex-row flex-wrap gap-1 items-center justify-center">
             <span class="fas fa-calendar-day m-1 text-neutral-800/80"></span>
-            <button
-                type="button"
+            <button type="button"
                 onclick={() => {
                     if ($events_loc.pres_mgmt.show_content__event_view == 'manage_files') {
                         $events_loc.pres_mgmt.show_content__event_view = null;
@@ -330,8 +329,7 @@
                 autocomplete="off"
                 class="form grow flex flex-row flex-wrap gap-1 justify-center items-center w-full"
             >
-                <button
-                    type="button"
+                <button type="button"
                     class="btn btn-sm mx-1 ae_btn_warning"
                     class:hidden={!$ae_loc.authenticated_access}
                     onclick={() => {
@@ -361,8 +359,7 @@
                     {/if}
                 </select>
 
-                <button
-                    type="button"
+                <button type="button"
                     onclick={() => {
                         $events_loc.pres_mgmt.fulltext_search_qry_str = '';
                         handle_search_trigger();