fix: prevent white screen on missing Firebase config, remove duplicate CSS imports, document missing TWO_FACTOR_ENCRYPTION_KEY

[iamsiddhant9]

📌 Description

Fixed a white screen crash that occurred when new contributors ran the frontend without a .env file configured. Also removed duplicate CSS @import blocks that were causing PostCSS build warnings and incorrect dark mode font rendering. Additionally added the missing TWO_FACTOR_ENCRYPTION_KEY to backend/.env.example so contributors know it is required to start the backend.

🛠 Changes Made

-frontend/src/utils/firebase.js — Wrapped Firebase initializeApp() in a try/catch block so the app loads gracefully instead of showing a white screen when Firebase API keys are missing from .env

-frontend/src/index.css — Removed two duplicate copies of the entire stylesheet that were causing @import must precede all other statements PostCSS errors and dark mode font color issues

-backend/.env.example — Added missing TWO_FACTOR_ENCRYPTION_KEY entry so new contributors know this required variable exists and how to generate it

✅ Checklist

• [Y] Code runs locally
• [Y] Followed project structure
• [Y] No console errors
• [Y] Properly tested changes
• Linked the issue

🚀 Notes for Reviewers

These fixes primarily improve the developer experience for new contributors. Before these changes, cloning the repo and running it locally without a .env file resulted in a blank white screen with no guidance. Now the app loads gracefully and logs clear error messages pointing contributors to the .env setup.

[iamsiddhant9]

Hello @aryandas2911, I have fixed #1817 kindly review it . "fix: prevent white screen on missing Firebase config, remove duplicate CSS imports, document missing TWO_FACTOR_ENCRYPTION_KEY"