chore(client): translate all user-visible strings to English

Mixed-language UI was confusing — onboarding said "Why DChain / How it
works / Your keys" in English headings but feature descriptions and
CTAs were in Russian; compose's confirm dialog was Russian; feed tabs
were Russian; error messages in humanizeTxError were Russian.
Everything user-facing is now English.

Files touched (only string literals, not comments):
  app/index.tsx              onboarding slides + CTA buttons
  app/(app)/compose.tsx      composer alerts, header button, placeholder,
                             attachment-size hint
  app/(app)/feed/index.tsx   tab labels (Following/For you/Trending),
                             empty-state hints, retry button
  app/(app)/feed/[id].tsx    post detail header + stats rows (Views,
                             Likes, Size, Paid to publish, Hosted on,
                             Hashtags)
  app/(app)/feed/tag/[tag].tsx  empty-state copy
  app/(app)/profile/[address].tsx  Profile header, Follow/Following,
                             Edit, Open chat, Address, Copied, Encryption,
                             Added, Members, unknown-contact hint
  app/(app)/new-contact.tsx  Search title, placeholder, Search button,
                             empty-state hint, E2E-ready indicator,
                             Intro label + placeholder, fee-tier labels
                             (Min / Standard / Priority), Send request,
                             Insufficient-balance alert, Request-sent
                             alert
  app/(app)/requests.tsx     Notifications title, empty-state, Accept /
                             Decline buttons, decline-confirm alert,
                             "wants to add you" line
  components/SearchBar.tsx   default placeholder
  components/feed/PostCard.tsx  long-press menu (Delete post, confirm,
                             Actions / Cancel)
  components/feed/ShareSheet.tsx  sheet title, contact-search placeholder,
                             empty state, Select contacts / Send button,
                             plural helper rewritten for English
  components/chat/PostRefCard.tsx  "POST" ribbon, "photo" indicator
  lib/api.ts                 humanizeTxError (rate-limit, clock skew,
                             bad signature, 400/5xx/network-error
                             messages)
  lib/dates.ts               dateBucket now returns Today/Yesterday/
                             "Jun 17, 2025"; month array switched to
                             English short forms

Code comments left in Russian intentionally — they're developer
context, not user-facing. This commit is purely display-string.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

client-app/lib/api.ts

@@ -79,23 +79,23 @@ async function post<T>(path: string, body: unknown): Promise<T> {
 export function humanizeTxError(e: unknown): string {
   const raw = e instanceof Error ? e.message : String(e);
   if (raw.startsWith('429')) {
-    return 'Слишком много запросов к ноде. Подождите пару секунд и попробуйте снова.';
+    return 'Too many requests to the node. Wait a couple of seconds and try again.';
   }
   if (raw.startsWith('400') && raw.includes('timestamp')) {
-    return 'Часы устройства не синхронизированы с нодой. Проверьте время на телефоне (±1 час).';
+    return 'Device clock is out of sync with the node. Check the time on your phone (±1 hour).';
   }
   if (raw.startsWith('400') && raw.includes('signature')) {
-    return 'Подпись транзакции невалидна. Попробуйте ещё раз; если не помогает — вероятна несовместимость версий клиента и ноды.';
+    return 'Transaction signature is invalid. Try again; if this persists the client and node versions may be incompatible.';
   }
   if (raw.startsWith('400')) {
-    return `Нода отклонила транзакцию: ${raw.replace(/^400:\s*/, '')}`;
+    return `Node rejected transaction: ${raw.replace(/^400:\s*/, '')}`;
   }
   if (raw.startsWith('5')) {
-    return `Ошибка ноды (${raw}). Попробуйте позже.`;
+    return `Node error (${raw}). Please try again later.`;
   }
   // Network-level
   if (raw.toLowerCase().includes('network request failed')) {
-    return 'Нет связи с нодой. Проверьте URL в настройках и доступность сервера.';
+    return 'Cannot reach the node. Check the URL in settings and that the server is online.';
   }
   return raw;
 }