refactor(converter): shared page layout + reusable conversion logic/UI

Pages:
- add WalletLayout route (WalletHeader + main + Footer via <Outlet/>),
  wrap converter/swap/bridge/transactions; thin pages, drop duplicated shell CSS
- extract SwapBridgeTabs shared between swap/bridge pages

Converter reuse (FSD layers, no widget->widget imports):
- move commission tiers to entities/commission (+ CommissionTable ui)
- shared calc hook features/payment/model/useCurrencyConversion;
  useConverterSection becomes thin wrapper; HomePage Converter reuses it
- move ConvertField/DirectionSwapButton to shared/ui; delete dead useConverter

Tooling:
- add eslint.config.js (ESLint 9 flat config); fix no-explicit-any in WalletPage

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/features/payment/model/useCurrencyConversion.ts

@@ -0,0 +1,102 @@
+import { useState } from 'react'
+import { useDebounce } from '@shared/lib/hooks/useDebounce'
+import { progressPercent } from '@entities/commission'
+import { GAS_PRICE, MIN_RUB_AMOUNT } from '@shared/config/constants'
+import type { ConvertFieldData } from '@shared/ui'
+import { usePaymentConfig } from '../hooks/usePaymentConfig'
+import { usePaymentQuote } from '../hooks/usePaymentQuote'
+import { usePaymentQuoteByRub } from '../hooks/usePaymentQuoteByRub'
+
+const TOO_LARGE_ERROR = 'Сумма слишком большая и превышает 600 000 ₽'
+
+const sanitize = (raw: string) => raw.replace(/[^0-9.]/g, '')
+
+interface Options {
+  /** Значение курса USDT/RUB до загрузки конфига (пилюля). */
+  rateFallback?: number
+}
+
+export function useCurrencyConversion({ rateFallback = 0 }: Options = {}) {
+  const [direction, setDirection] = useState<'usdt_to_rub' | 'rub_to_usdt'>('usdt_to_rub')
+  const [usdtInput, setUsdtInput] = useState('1000')
+  const [rubInput, setRubInput] = useState(String(MIN_RUB_AMOUNT))
+
+  const { data: config } = usePaymentConfig()
+  const configUsdtRate = Number(config?.usdt_exchange_rate) || rateFallback
+  const gasPriceRub = Number(config?.gas_fee) || GAS_PRICE
+
+  const isUsdtToRub = direction === 'usdt_to_rub'
+
+  const numUsdt = Number.parseFloat(usdtInput) || 0
+  const debouncedUsdt = useDebounce(numUsdt, 400)
+  const { data: quoteUsdtToRub, isError: quoteError } = usePaymentQuote(isUsdtToRub ? debouncedUsdt : 0)
+
+  const numRubInput = Number.parseFloat(rubInput) || 0
+  const debouncedRub = useDebounce(numRubInput, 400)
+  const { data: quoteRubToUsdt, isError: quoteRubError } = usePaymentQuoteByRub(!isUsdtToRub ? debouncedRub : 0)
+
+  const rubBelowMin = !isUsdtToRub && numRubInput > 0 && numRubInput < MIN_RUB_AMOUNT
+
+  const rubTotal = quoteUsdtToRub?.total_price ?? ''
+  const rubTotalNum = Number(rubTotal) || 0
+  const usdtFromRub = quoteRubToUsdt?.usdt_amount ?? ''
+  const usdtFromRubNum = Number(usdtFromRub) || 0
+
+  const commission = isUsdtToRub
+    ? Number(quoteUsdtToRub?.service_fee) || 0
+    : Number(quoteRubToUsdt?.service_fee) || 0
+
+  const displayRubAmount = isUsdtToRub ? rubTotalNum : numRubInput
+  const effectiveRate = isUsdtToRub
+    ? (numUsdt > 0 ? rubTotalNum / numUsdt : 0)
+    : (usdtFromRubNum > 0 ? numRubInput / usdtFromRubNum : 0)
+
+  function onSwap() {
+    setDirection(d => (d === 'usdt_to_rub' ? 'rub_to_usdt' : 'usdt_to_rub'))
+  }
+
+  const convert: ConvertFieldData = isUsdtToRub
+    ? {
+        value: usdtInput,
+        currency: 'USDT',
+        onChange: (raw) => setUsdtInput(sanitize(raw)),
+        error: quoteError ? TOO_LARGE_ERROR : undefined,
+      }
+    : {
+        value: rubInput,
+        currency: 'RUB',
+        onChange: (raw) => setRubInput(sanitize(raw)),
+        error: rubBelowMin
+          ? `Минимальная сумма: ${MIN_RUB_AMOUNT.toLocaleString('ru-RU')} ₽`
+          : quoteRubError
+            ? TOO_LARGE_ERROR
+            : undefined,
+      }
+
+  const pay: ConvertFieldData = isUsdtToRub
+    ? { value: rubTotal, currency: 'RUB' }
+    : { value: usdtFromRub, currency: 'USDT' }
+
+  return {
+    isUsdtToRub,
+    gasPriceRub,
+    configUsdtRate,
+    convert,
+    pay,
+    onSwap,
+    commission: {
+      amount: displayRubAmount,
+      progress: progressPercent(displayRubAmount),
+      commission,
+      effectiveRate,
+    },
+    // сырые значения для создания ордера и валидации в обёртках
+    numUsdt,
+    usdtFromRubNum,
+    rubTotal,
+    rubTotalNum,
+    numRubInput,
+    usdtFromRub,
+    rubBelowMin,
+  }
+}