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/widgets/wallet-layout/ui/WalletLayout.tsx

@@ -0,0 +1,21 @@
+import { Outlet } from 'react-router-dom'
+import { WalletHeader } from '@widgets/wallet-header'
+import { Footer } from '@widgets/footer'
+import styles from './WalletLayout.module.css'
+
+interface Props {
+  footer?: boolean
+  center?: boolean
+}
+
+export function WalletLayout({ footer = false, center = false }: Props) {
+  return (
+    <div className={styles.page}>
+      <WalletHeader />
+      <main className={center ? `${styles.main} ${styles.center}` : styles.main}>
+        <Outlet />
+      </main>
+      {footer && <Footer />}
+    </div>
+  )
+}