feat: improved sidebar UI with larger icons and user info in footer

- Increased all sidebar navigation icons from text-sm to text-xl for better visibility
- Moved user information and logout button from header to sidebar footer
- Added user avatar with name and email in expanded sidebar state
- Collapsed sidebar shows avatar icon and logout icon button stacked vertically
- Simplified header by removing user badge and logout button
- Added version info (v1.0.0) in sidebar footer
- Improved responsive design for both collapsed and expanded states

postcss.config.cjs

@@ -0,0 +1,6 @@
+module.exports = {
+  plugins: {
+    tailwindcss: {},
+    autoprefixer: {}
+  }
+};