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

src/routes/events/[event_id]/(leads)/leads/ae_comp__exhibit_search.svelte

@@ -91,8 +91,7 @@
                 Search
             </button>
 
-            <button
-                type="button"
+            <button type="button"
                 class:hidden={!$events_loc.leads.qry__search_text}
                 onclick={() => {
                     $events_loc.leads.qry__search_text = '';

src/routes/events/[event_id]/(leads)/leads/exhibit/[exhibit_id]/+page.svelte

@@ -185,7 +185,7 @@
             <p class="opacity-50">Booth #{$lq__exhibit_obj?.code ?? '...'}</p>
         </div>
         <div class="flex gap-2">
-            <button class="btn preset-tonal-secondary" onclick={handle_export}>
+            <button type="button" class="btn preset-tonal-secondary" onclick={handle_export}>
                 <Download size="1.25em" class="mr-2" /> Export CSV
             </button>
             <a href={`/events/${page.params.event_id}/leads/exhibit/${page.params.exhibit_id}/scan`} class="btn preset-filled-primary">

src/routes/events/[event_id]/(leads)/leads/exhibit/[exhibit_id]/ae_comp__exhibit_tracking_search.svelte

@@ -90,8 +90,7 @@
                 Search
             </button>
 
-            <button
-                type="button"
+            <button type="button"
                 class:hidden={!$events_loc.leads.tracking__qry__search_text}
                 onclick={() => {
                     $events_loc.leads.tracking__qry__search_text = '';