### 🎯 Authentication & Signup Improvements
- ✅ Fixed login to work with both username AND email
- ✅ Added username availability check (real-time validation)
- ✅ Enhanced error messages for login/signup failures
- ✅ Added loading states and success feedback
- ✅ Improved signup flow with better validation
- ✅ Added comprehensive error handling

### 📱 Mobile UX Enhancements
- ✅ Fixed bottom navigation overlap issues
- ✅ Made all modals mobile-responsive
- ✅ Centered settings modal for better visibility
- ✅ Fixed sign out button visibility on mobile
- ✅ Improved toast notifications (4s duration, z-index 9999)
- ✅ Enhanced username availability feedback (color-coded borders)

### 👤 Profile Management
- ✅ Implemented full profile editing (name, username, DOB, gender, occupation, location)
- ✅ Added avatar upload preview functionality
- ✅ Real-time username availability checking
- ✅ Profile settings modal with scrollable content
- ✅ Added camera icon for profile picture upload

### 🎯 Habit Settings
- ✅ Made create habit modal fully responsive
- ✅ Fixed button visibility issues on mobile
- ✅ Improved scrolling and layout
- ✅ Added navigation from profile settings to habits

### 🔧 Backend Improvements
- ✅ Fixed username-to-email lookup for login
- ✅ Made username availability endpoint public (no auth required)
- ✅ Added friend suggestions endpoint
- ✅ Enhanced error logging and debugging
- ✅ Better error messages for authentication

### 🎨 UI/UX Polish
- ✅ Enhanced Toast component (responsive sizing, longer duration)
- ✅ Color-coded username status (green for available, red for taken)
- ✅ Removed empty spaces in signup form
- ✅ Consistent button sizing and spacing
- ✅ Better visual feedback for all user actions

### 🐛 Bug Fixes
- ✅ Fixed settings modal cut-off issues on mobile
- ✅ Fixed username availability not showing
- ✅ Fixed login errors not displaying
- ✅ Fixed modal height issues on small screens
- ✅ Fixed button overlap with bottom navigation