feat: real-time currency conversion with external API integration and fallback strategy

[wellnerds]

Description
This PR enhances the currency conversion API by introducing real-time exchange rate retrieval via external API integration, along with a robust fallback mechanism to ensure reliability.

Key Improvements
🔄 Real-time currency conversion using external API
🛡️ Fallback strategy to handle API failures gracefully
🧱 Clean architecture with separation of concerns (Controller, Service)
📦 PSR-4 autoloading via Composer
🧪 Unit tests updated to support fallback and ensure reliability
🌐 RESTful endpoint design:
GET /exchange/{amount}/{from}/{to}
🧠 Technical Decisions
Implemented a dedicated service layer to isolate business logic and external API consumption.
Applied fallback rates to guarantee consistent responses even in case of external API downtime.
Ensured code readability, maintainability, and scalability following SOLID principles.
🔍 How to Test
composer install
php -S localhost:8000 src/index.php

Example:

http://localhost:8000/exchange/10/BRL/USD

This implementation focuses on production-ready patterns, including resilience, maintainability, and clear separation of responsibilities.

🙋‍♂️ Final Considerations

I’m available for any feedback or code review discussions.

Thank you for the opportunity — I’m ready to contribute and start immediately.

All requirements were implemented and validated locally (tests and lint passing).

I’m available for further improvements and feedback.

Looking forward to contributing to the team.

[wellnerds]

Ready for review. All requirements implemented and tested locally.

[wellnerds]

🚀 Improvements: Real-Time Currency Conversion + CI Fix

This PR enhances the application by introducing a real-time currency conversion mechanism using an external API, along with a robust fallback strategy.

🔧 What was done

• Implemented external exchange rate provider
• Removed hardcoded rate dependency
• Added fallback mechanism for resilience
• Refactored service layer for better separation of concerns
• Fixed merge conflicts in composer.json
• Regenerated composer.lock to ensure dependency consistency

✅ Why this matters

• Improves realism with live exchange rates
• Increases reliability with fallback handling
• Aligns project with production-ready standards
• Restores CI pipeline integrity

🧪 Tests

• Existing tests updated and passing
• Application tested via endpoint:
  /exchange/{amount}/{from}/{to}

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This implementation focuses on maintainability, resilience, and clean architecture principles.