Issue 95 - Feature: Set up environment configuration system

[Raafay-Qureshi]

Description

This Pull Request sets up a centralized environment configuration system that validates all required variables when the app starts. Instead of scattering process.env calls throughout the codebase, everything now goes through a single validated config module with TypeScript type safety.

The config system supports development, production, and test environments, and includes helper functions to check which environment we're running in.

Changes Made

• Created env.config.ts with TypeScript Config interface
• Implemented validation that fails fast if required variables are missing
• Added PORT validation (must be valid number 0-65535)
• Added support for all required environment variables:
  • Server: PORT, NODE_ENV
  • Database: MONGODB_URI
  • Authentication: JWT_SECRET, JWT_EXPIRES_IN
  • CORS: ALLOWED_ORIGINS
  • Email: EMAIL_SERVICE, EMAIL_USER, EMAIL_PASS
• Updated all existing files in backend/src to use centralized config
• Removed duplicate dotenv.config() calls
• Added helper functions: isDevelopment(), isProduction(), isTest()
• Updated .env and .env.example with all required variables

Testing

Manually tested:

• App starts normally with valid config
• App crashes immediately with helpful error when variables are missing
• PORT validation catches invalid values like "abc" or negative numbers
• Production mode correctly uses specified CORS origins
• Development mode allows all localhost requests

Files Modified

• backend/src/config/env.config.ts (new)
• backend/src/config/db.ts
• backend/src/index.ts
• backend/src/middleware/errorMiddleware.ts
• backend/src/routes/statusRoutes.ts
• backend/src/routes/index.ts
• backend/.env
• backend/.env.example

Closes #95