Frontend: Complete Next.js implementation

Core Features:
- ✅ Authentication (login/register pages)
- ✅ Main layout with sidebar
- ✅ Channel list and navigation
- ✅ Channel page with real-time messaging
- ✅ Direct messages (DMs) page
- ✅ Message components (list, input)
- ✅ WebSocket integration for real-time updates
- ✅ Typing indicators
- ✅ Online status indicators
- ✅ Stores (auth, channels, messages)
- ✅ API client with JWT auth
- ✅ Socket.IO client wrapper
- ✅ Responsive UI with Tailwind

Tech Stack:
- Next.js 14 (App Router)
- TypeScript
- TailwindCSS
- Socket.IO client
- Zustand (state management)
- Axios (HTTP client)
- date-fns (date formatting)
- lucide-react (icons)

Build Status: ✅ Successfully compiles
Production Ready: ✅ Optimized build generated

frontend/tailwind.config.ts

@@ -0,0 +1,19 @@
+import type { Config } from "tailwindcss";
+
+const config: Config = {
+  content: [
+    "./src/pages/**/*.{js,ts,jsx,tsx,mdx}",
+    "./src/components/**/*.{js,ts,jsx,tsx,mdx}",
+    "./src/app/**/*.{js,ts,jsx,tsx,mdx}",
+  ],
+  theme: {
+    extend: {
+      colors: {
+        background: "var(--background)",
+        foreground: "var(--foreground)",
+      },
+    },
+  },
+  plugins: [],
+};
+export default config;