refactor(launcher): standardize helper names and apply batch formatting

- Renamed internal 'preventDefault' to 'prevent_default' in launcher files.
- Fixed native 'event.preventDefault()' call in launcher_file_cont.svelte.
- Applied batch formatting (printWidth: 80) across the (launcher) module.

src/routes/events/[event_id]/(launcher)/+layout.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
     /**
      * events/[event_id]/(launcher)/+layout.svelte
-     * Root layout for the launcher area. 
+     * Root layout for the launcher area.
      * Ensures background sync runs globally regardless of active tab.
      */
     import { ae_loc } from '$lib/stores/ae_stores';