Add splash screen with bitvault logo

[cryptoquick]

Splash Screen Implementation Changelog

Added

• New SplashScreen variant to the View enum
• Added splash_timer field to AppState to track the 1-second display time
• Implemented render_splash_screen method with:
  • Black background
  • Centered logo at 50% scale
  • Efficient image loading using OnceLock
  • Proper error handling for image loading

Modified

• Updated BitVaultApp::new() to start with the splash screen view
• Enhanced update() method to:
  • Track splash screen timer
  • Request continuous repaints during splash screen display
  • Transition to appropriate view (Home or LockScreen) after splash screen

Technical Details

• Used standard library's OnceLock for thread-safe, one-time image loading
• Added multiple path resolution to find the splash logo image
• Implemented atomic counter to track render calls for debugging
• Added appropriate logging at trace and debug levels
• Ensured timer starts immediately without requiring user interaction

Performance Optimizations

• Image is loaded only once and reused across frames
• Timer updates consistently at 60 FPS
• Minimal memory footprint with efficient image handling