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)/launcher/+layout.svelte

@@ -272,6 +272,7 @@
                         filename: obj_filename,
                         key: $ae_api.account_id
                     },
+                    filename: obj_filename,
                     return_blob: true,
                     auto_download: true,
                     log_lvl: 1