Add 3D character rendering to Character3D component

- Integrated Three.js for 3D character visualization based on user gender and age.
- Simplified the character structure by removing outdated HTML elements and replacing them with a dynamic 3D model loader.
- Implemented model loading with fallback options and added animation capabilities for enhanced visual appeal.
- Updated CSS for the character container to ensure proper rendering and responsiveness.

frontend/package.json

@@ -21,6 +21,7 @@
     "dotenv": "^16.4.5",
     "mitt": "^3.0.1",
     "socket.io-client": "^4.8.1",
+    "three": "^0.169.0",
     "vue": "~3.4.31",
     "vue-i18n": "^10.0.0-beta.2",
     "vue-multiselect": "^3.1.0",