feat: integrate HeroUI component library

Implemented HeroUI migration plan with the following changes:

Stage 0: Environment Setup
- Installed @heroui/react@2.8.7, @heroui/theme@2.4.26, framer-motion@12.29.2
- Configured Tailwind with HeroUI plugin
- Added HeroUI content paths to Tailwind config

Stage 1: Provider Architecture
- Created Providers.tsx wrapper combining HeroUIProvider and AppProvider
- Updated app/layout.tsx to use new Providers component
- Preserved all AppContext functionality (theme, language, translations)

Stage 2: Component Migrations
- TabNavigation: Migrated to HeroUI Tabs with keyboard navigation support
- TopBar: Migrated buttons to HeroUI Button components
- LanguageSwitch: Migrated to HeroUI Dropdown for better UX
- ThemeSwitch: Migrated to HeroUI Button (isIconOnly variant)
- MintSwapPanel: Migrated to HeroUI Tabs and Button components

Benefits:
- Enhanced accessibility with ARIA attributes and keyboard navigation
- Smooth animations and transitions via Framer Motion
- Consistent component API across the application
- Maintained all existing design tokens and color system
- Preserved dark mode functionality

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

components/Providers.tsx

@@ -0,0 +1,13 @@
+"use client";
+
+import { HeroUIProvider } from "@heroui/react";
+import { AppProvider } from "@/contexts/AppContext";
+import { ReactNode } from "react";
+
+export function Providers({ children }: { children: ReactNode }) {
+  return (
+    <HeroUIProvider>
+      <AppProvider>{children}</AppProvider>
+    </HeroUIProvider>
+  );
+}