Major Admin Panel Updates: Logo Management, Profile System, and UI Improvements

- Replaced Navbar Images with dedicated Logo Upload system
- Created comprehensive Admin Profile management page
- Added profile image display in sidebar and mobile header
- Removed statistics sections from Activities page for cleaner UI
- Fixed Upazila filter persistence after page reload
- Enhanced mobile responsiveness and user experience
- Added password change functionality with validation
- Implemented activity logging for all admin actions
- Updated navigation and dashboard statistics
- Improved form validation and error handling
