Fix: standardize loading and error handling in papers page

[alok-108]

Title: Fix inconsistent loading and error handling in papers page

Description: ## Problem
The application has inconsistent loading and error handling across components.

Solution

Added explicit loading state and error handling in papers page using standard React hooks and the Fetch API, to replace previous obscure abstractions.

Implementation

• Updated API logic using try-catch blocks
• Added conditional rendering for Loading... and manual generic text error blocks

Testing

• Verified loading state locally
• Tested API failure scenario by simulating erroneous endpoints
• Checked UI to ensure robust transition states

Screenhots (if any):

Resolves : Standardizing loading and error states across the articles listing page.