Refactor file upload to use SDK instead of XMLHttpRequest

Replaced manual XMLHttpRequest implementation with the SDK's `uploadFile` method for handling file uploads to presigned URLs. This simplifies the code, leverages built-in features like progress tracking, and improves error handling. Added token extraction and upload progress updates to maintain functionality.

backend/app/main.py

@@ -17,7 +17,8 @@ logger.info(f"Starting app!!!")
 app = FastAPI(
     title=settings.PROJECT_NAME,
     version=settings.VERSION,
-    openapi_url=f"{settings.API_VERSION_STR}/openapi.json"
+    openapi_url=f"{settings.API_VERSION_STR}/openapi.json",
+    debug=True,
 )
 
 # Set up CORS middleware