fix(launcher): resolve 'download' filename bug and refactor data_url to global page state

- Updated 'handle_open_file' in launcher_file_cont.svelte to correctly pass filename to API.
- Fixed WebSocket ae_download command in launcher layout to include filename.
- Implemented a safety net in api_get_object.ts to extract filename from params if missing.
- Added 'download' attribute to Hosted Files download button for direct links.
- Refactored launcher menu components to use Svelte 5 global 'page' state instead of obsolete 'data_url' prop.

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

@@ -4,8 +4,8 @@
      * Root layout for the launcher area.
      * Ensures background sync runs globally regardless of active tab.
      */
-    import { ae_loc } from '$lib/stores/ae_stores';
-    import LauncherBackgroundSync from './launcher_background_sync.svelte';
+    // import { ae_loc } from '$lib/stores/ae_stores';
+    import Launcher_Background_Sync from './launcher_background_sync.svelte';
 
     interface Props {
         children?: import('svelte').Snippet;
@@ -15,7 +15,7 @@
 </script>
 
 <!-- Background Sync Process (Invisible) -->
-<LauncherBackgroundSync log_lvl={1} />
+<Launcher_Background_Sync log_lvl={1} />
 
 <!-- Render the rest of the launcher UI -->
 {@render children?.()}