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/api/client.ts

@@ -7,6 +7,7 @@ import {
   safeRedirectToLogin,
 } from '../utils/token';
 import { useBlockingStore } from '../store/blocking';
+import { API } from '../config/constants';
 
 const API_BASE_URL = import.meta.env.VITE_API_URL || '/api';
 
@@ -57,6 +58,7 @@ const getTelegramInitData = (): string | null => {
 
 export const apiClient = axios.create({
   baseURL: API_BASE_URL,
+  timeout: API.TIMEOUT_MS,
   headers: {
     'Content-Type': 'application/json',
   },