Add list/table view for sessions panel alongside tiles view

- Toggle buttons (Tiles/List) in sessions header, preference
  persisted in localStorage
- List view: table with Name, Date, Duration, Messages, Mode, Actions
  columns; same fields and buttons as tiles, just tabular layout
- Refactored loadSessions() into buildGridHTML/buildListHTML helpers
  with shared attachSessionListeners() for both views
- i18n: Tiles, List, Name, Date, Duration, Messages, Mode, Actions
  keys added to LANG_RU
- Bump 1.22.6, SW cache v37->v38

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simtrace-analyser-v37';
+const CACHE = 'simtrace-analyser-v38';
 
 const PRECACHE = [
     'index.html',