This PR introduces a comprehensive UI upgrade to improve user experience while maintaining all existing functionality. Key improvements include:

1. Welcome Screen:

1. Added glass-morphism effect with beautiful shadows
2. Enhanced robot animation with hover effects
3. Improved typography and text shadows
4. Gradient background for depth

2. Chat Container:

1. Modern message bubbles with better spacing
2. Custom scrollbar styling
3. Improved header with user status
4. Better responsive design

Files Changed:

• src/components/Welcome.js (updated)
• src/components/ChatContainer.js (updated)

Steps to Test:

1. Login and verify the new welcome screen animations
2. Check chat message bubbles in different screen sizes
3. Verify hover effects on interactive elements
4. Test scroll behavior in chat window

Screenshots:

• Screenshot 2025年05月11日 155015
• Screenshot 2025年05月11日 155038