chore(onboarding): delete the dead first-run components and their orphaned strings (#1488)

The activation analysis (2026-08-07) verified these have zero importers or
triggers; the new stepped checklist and its PostHog funnel replaced their
roles:

- SuccessAnimation (confetti variant): never mounted, and the completion
  moment is now the quiet check-morph signature, so it will stay unused
- AgentSetupBanner, ConsultantEmptyState: never mounted
- EmptyReceipts + its Camera import: only consumer of the preset_receipts_*
  strings and of a /receipts/scan route that does not exist
- new_user_checklist i18n namespace (24 keys x 2 locales): the old wizard
  copy; the live checklist reads initial_setup

The onboarding.empty agent intent stays: it is registered in the intent
table and reachable via /api/agent/invoke, so removing it is a product
decision, not dead-code removal.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

components/ui/empty-state.tsx

@@ -9,7 +9,6 @@ import {
   ReceiptText,
   Users,
   ArrowLeftRight,
-  Camera,
   Building2,
   FileText,
   Calendar,
@@ -141,19 +140,6 @@ export function EmptyTransactions() {
   )
 }
 
-export function EmptyReceipts() {
-  const t = useTranslations('empty')
-  return (
-    <EmptyState
-      icon={Camera}
-      title={t('preset_receipts_title')}
-      description={t('preset_receipts_description')}
-      actionLabel={t('preset_receipts_action')}
-      actionHref="/receipts/scan"
-    />
-  )
-}
-
 export function EmptyDeadlines() {
   const t = useTranslations('empty')
   return (