fix(upload): update hosted file upload endpoint to V3 action path

The legacy /hosted_file/upload_files router was decommissioned (commented
out in registry.py). Both upload components now point to the active V3
endpoint at /v3/action/hosted_file/upload. Response shape is identical
so no consumer-side changes needed.

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

src/routes/events/ae_comp__event_files_upload.svelte

@@ -151,7 +151,7 @@ async function handle_input_upload_files({
     ae_promises.upload__hosted_file_obj = api
         .post_object({
             api_cfg: $ae_api,
-            endpoint: '/hosted_file/upload_files',
+            endpoint: '/v3/action/hosted_file/upload',
             form_data: form_data,
             task_id: task_id,
             log_lvl: log_lvl