Refactor authentication and theme context usage

- Moved authentication hooks and context to a dedicated hooks directory.
- Updated imports in various components and pages to use the new hooks.
- Created AuthContext and ThemeContext for better state management.
- Refactored ThemeProvider to utilize the new ThemeContext.
- Cleaned up sidebar and button components for consistency and readability.
- Ensured all components are using the latest context and hooks for authentication and theme management.

src/pages/DashboardPage.tsx

@@ -1,6 +1,6 @@
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card'
 import { Button } from '@/components/ui/button'
-import { useAuth } from '@/contexts/AuthContext'
+import { useAuth } from '@/hooks/use-auth'
 import { Link } from 'react-router'
 
 export function DashboardPage() {