Pull Request: Externalize Hardcoded Configurations (#118)

[JerryIdoko]

📝 Description
This PR refactors the backend services to remove sensitive and environment-specific hardcoded values (such as API keys, database URLs, and Soroban contract IDs). I have implemented a centralized configuration management system that leverages environment variables and includes strict schema validation to prevent the server from starting with a misconfigured state.

🎯 Key Changes
Environment Abstraction: Removed hardcoded strings from all service files and replaced them with calls to a centralized config object.

Validation Layer: Integrated a validation schema (using Joi or Zod) to ensure that required variables (like DATABASE_URL or JWT_SECRET) are present and follow the correct format before the application initializes.

Template Creation: Added a .env.example file to the root directory to serve as a blueprint for other developers and deployment environments.

Documentation: Updated the README.md with a "Configuration" section detailing each environment variable and its purpose.

🛡️ Implementation Detail: Safe Configuration Loading
Instead of accessing process.env directly throughout the app, I've implemented a pattern that fails fast if a variable is missing:

TypeScript
// src/config/index.ts
import dotenv from 'dotenv';
dotenv.config();

export const config = {
port: parseInt(process.env.PORT || '3000', 10),
dbUrl: process.env.DATABASE_URL || throw new Error("DATABASE_URL is required"),
sorobanNetwork: process.env.SOROBAN_NETWORK || 'testnet',
};
✅ Acceptance Criteria Checklist
[x] No Hardcoding: All sensitive strings and environment-specific flags are moved to .env.

[x] Validation: The application throws a clear error if critical environment variables are missing at startup.

[x] Documentation: .env.example is provided and documented.

🚀 How to Verify
Setup Environment: Copy the example file: cp .env.example .env.

Fill Values: Populate the .env with your local development credentials.

Run Application: npm start.

Negative Test: Temporarily comment out a required variable in .env and verify that the application crashes with a descriptive configuration error.

🔗 Linked Issues
Closes #118

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