Add live avatar preview panel for real-time frame customization

[darshan02parmar]

Description
Currently, users have to click "Generate" to see their framed avatar.
This PR adds a real-time live preview panel that updates instantly as users change:

• Theme
• Accent color
• Canvas background
• Shape / style

Implementation

• Added a small preview component beside the controls.
• Bound preview updates to state changes in React:
  • Theme selector → updates preview
  • Accent color input → updates preview
  • Canvas background selector → updates preview
  • Shape/style selector → updates preview
• Uses the same API URL format, but preview is rendered on the frontend without hitting the API every time

I'd like to work on this issue ,,Assign it to me @ashmeet07