fix(pres_mgmt): increase file upload timeout to 20 min, guard null result

- Set post_object timeout to 1200000ms (20 min) for hosted file uploads;
  the 90s default was killing large presentation file uploads
- Guard result[0] access in .then() to prevent crash when upload
  times out or is aborted (TypeError: can't access property "hosted_file_id")

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/routes/events/ae_comp__event_files_upload.svelte

@@ -153,11 +153,16 @@ async function handle_input_upload_files({
             api_cfg: $ae_api,
             endpoint: '/v3/action/hosted_file/upload',
             form_data: form_data,
+            timeout: 1200000, // 20 minutes — large presentation files can be very slow to upload
             task_id: task_id,
             log_lvl: log_lvl
         })
         .then(async function (result) {
             // WARNING: endpoint returns a list, we sequentially handle one at a time.
+            if (!result || !result[0]) {
+                console.error('Upload failed or timed out — no result returned.');
+                return false;
+            }
             const hosted_file_obj = result[0];
             const hosted_file_id = hosted_file_obj.hosted_file_id;