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_menu.svelte

@@ -1,7 +1,5 @@
 <script lang="ts">
     interface Props {
-        data_url: any;
-
         lq__event_obj: any;
 
         lq__event_event_file_obj_li: any;
@@ -28,8 +26,6 @@
     }
 
     let {
-        data_url,
-
         lq__event_obj,
 
         lq__event_event_file_obj_li,
@@ -168,7 +164,6 @@
 
     {#if $ae_loc.edit_mode}
         <Menu_location_list_menu
-            {data_url}
             {lq__event_location_obj_li}
             slct_event_location_id={$events_slct.event_location_id}
             bind:loading__session_li_status
@@ -213,7 +208,6 @@
 
     {#if $lq__event_session_obj_li}
         <Menu_session_list_menu
-            {data_url}
             bind:slct__event_session_id
             bind:loading__session_id_status
             {lq__event_session_obj_li}