refactor: full codebase cleanup, dependency updates, and lint fixes

Phase 0: Remove ~920 lines of dead code (ThemeBentoPicker, PromoDiscountBadge,
AdminLayout, SettingsSidebar, MovingGradient, EmptyState, miniapp API, unused
types/functions/transitions/skeleton helpers). Fix API barrel file (add 20 missing exports).

Phase 1: Add ErrorBoundary (app/page/widget levels), centralize constants,
add axios timeout, fix staleTime:0 in React Query.

Phase 2: Consolidate hexToHsl, extract email validation, fix duplicate code.

Phase 3: Fix auth race condition (await checkAdminStatus), memoize useCurrency,
add WebSocket message validation.

Phase 4: Extract useBranding, useFeatureFlags, useScrollRestoration from AppShell.

Phase 5: Remove all eslint-disable react-hooks/exhaustive-deps (14 total),
simplify logger, remove deprecated hooks (useBackButton, useTelegramDnd,
useTelegramWebApp).

Dependencies: React 19, react-router 7, zustand 5, i18next 25, react-i18next 16,
eslint-plugin-react-refresh 0.5. Remove unused @lottiefiles/dotlottie-react.
Convert vite manualChunks to function-based approach for react-router v7 compat.

Lint: Fix logger.ts no-unused-expressions, fix react-refresh/only-export-components
in 6 Radix primitive files (const re-exports → direct re-exports), fix
WebSocketProvider exhaustive-deps. Result: 0 errors, 0 warnings.

Add CLAUDE.md to .gitignore.

src/pages/AdminUserDetail.tsx

@@ -1,5 +1,5 @@
 import { useState, useEffect, useCallback } from 'react';
-import { useParams, useNavigate } from 'react-router-dom';
+import { useParams, useNavigate } from 'react-router';
 import { useTranslation } from 'react-i18next';
 import i18n from '../i18n';
 import { useCurrency } from '../hooks/useCurrency';
@@ -11,7 +11,6 @@ import {
   type UpdateSubscriptionRequest,
 } from '../api/adminUsers';
 import { AdminBackButton } from '../components/admin';
-import { useBackButton } from '../platform/hooks/useBackButton';
 
 // ============ Icons ============
 
@@ -82,8 +81,6 @@ export default function AdminUserDetail() {
   const navigate = useNavigate();
   const { id } = useParams<{ id: string }>();
 
-  useBackButton(() => navigate('/admin/users'));
-
   const localeMap: Record<string, string> = { ru: 'ru-RU', en: 'en-US', zh: 'zh-CN', fa: 'fa-IR' };
   const locale = localeMap[i18n.language] || 'ru-RU';