fix: loyalty tier crash, chat duplicate rooms, sidebar defaults

- LoyaltyPage: levelBadge() now falls back to bronze for unknown tiers
  (DB had loyalty_tier='standard' from old seed data)
- migration 040: deduplicate general chat rooms + add unique index,
  normalize loyalty_tier to bronze for non-standard values
- chat.ts: ON CONFLICT clause now targets the new partial unique index
- Sidebar: DEFAULT_GROUPS only opens 'basics' by default; bump
  localStorage key to sidebarGroups_v2 to clear stale stored state

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

src/pages/LoyaltyPage.tsx

@@ -214,8 +214,9 @@ const MANUAL_REASONS = [
   'Другое',
 ]
 
-function levelBadge(levelId: LevelId) {
-  const level = DEFAULT_LEVELS.find(l => l.id === levelId)!
+function levelBadge(levelId: string) {
+  const level = DEFAULT_LEVELS.find(l => l.id === levelId) ?? DEFAULT_LEVELS[0]
+  const safeId = (DEFAULT_LEVELS.find(l => l.id === levelId)?.id ?? 'bronze') as LevelId
   const bgs: Record<LevelId, string> = {
     bronze:   'bg-amber-100 text-amber-700 dark:bg-amber-900/30 dark:text-amber-400',
     silver:   'bg-slate-100 text-slate-600 dark:bg-slate-700 dark:text-slate-300',
@@ -223,7 +224,7 @@ function levelBadge(levelId: LevelId) {
     platinum: 'bg-violet-100 text-violet-700 dark:bg-violet-900/30 dark:text-violet-400',
   }
   return (
-    <span className={cn('inline-flex items-center gap-1 px-2 py-0.5 rounded-full text-xs font-semibold', bgs[levelId])}>
+    <span className={cn('inline-flex items-center gap-1 px-2 py-0.5 rounded-full text-xs font-semibold', bgs[safeId])}>
       <level.icon size={10} />
       {level.name}
     </span>