fix(launcher): hidden sessions collapse space, sort by datetime, rename internal-file flag

- menu_session_list: move class:hidden to <li> so fixed-height rows fully collapse
- launcher/+layout.svelte: sort sessions by start_datetime (ascending) instead of name
- Rename hide_content__draft_files → show_content__internal_files (default false);
  remove redundant show_content__draft_files; rename prop hide_draft →
  show_internal_purpose_files in launcher_file_cont; update all 7 call sites and
  the menu_launcher_controls toggle. Now hides admin/draft/outline purpose files
  by default with consistent naming across the flag, prop, and toggle.

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

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

@@ -298,11 +298,10 @@ let lq__event_session_obj_li = $derived.by(() => {
         if (!id) return [];
         if (log_lvl > 1)
             console.log(`LQ - Event Session list location_id: ${id}`);
-        // Note: .reverse() before .sortBy() is a no-op — sortBy always re-sorts.
         return await db_events.session
             .where('event_location_id')
             .equals(id)
-            .sortBy('name');
+            .sortBy('start_datetime');
     });
 });