feat: Complete LPM password manager with enhanced UI and backup features
- Add startup screen with 1.5s display and centered branding
- Implement "Show Password" checkboxes across all password entry dialogs
- Center all windows and dialogs on screen for better UX
- Add Settings page with Backup and USB Backup functionality
- Create USB backup feature that detects drives and copies vault/salt files
- Add custom LPM icon with keyhole design throughout the application
- Implement system dark mode detection for macOS
- Optimize window dimensions for all dialogs (master password, add entry, settings)
- Add Settings button positioned at bottom of main window
- Improve button layout and responsiveness in main interface
- Fix various UI spacing and sizing issues
- Add comprehensive error handling for file operations
- Ensure cross-platform compatibility (macOS/Windows)
- Update requirements.txt with necessary dependencies
- Prepare for PyInstaller packaging with proper icon support
UI/UX Improvements:
- Compact, centered design with proper spacing
- Consistent theming and visual hierarchy
- Responsive button layouts that adapt to window resizing
- Professional branding with custom icon integration
Security Features:
- Local encrypted password storage with salt
- Master password protection
- Secure password generation
- Backup functionality for data safety
Technical Enhancements:
- Modular code structure with reusable functions
- Comprehensive error handling and user feedback
- Cross-platform file system operations
- Proper window management and centering