feat: implement REST API for message queue operations

[nebjak]

Adds a complete HTTP REST API with JSON endpoints for all message queue operations.

Features:

• POST /add - Add message (returns created Message object)
• POST /get - Retrieve messages with count parameter
• POST /delete - Delete messages by IDs
• POST /purge - Clear all messages
• POST /retry - Retry failed messages
• GET /hello - Health check endpoint

Implementation:

• Axum web framework with JSON request/response
• Comprehensive integration test suite
• Input validation and error handling
• Returns full Message objects (not just success strings)

Breaking Change:

• New API endpoints require HTTP clients instead of direct library usage

[Copilot]

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

[Copilot]

Pull Request Overview

This PR implements a complete REST API for message queue operations using the Axum web framework. The API provides JSON endpoints for all message queue operations including adding, retrieving, deleting, purging, and retrying messages, along with a health check endpoint.

Key changes:

• Complete REST API implementation with JSON request/response handling
• Comprehensive integration test suite covering all endpoints
• Service layer refactoring to use Arc for thread safety

Reviewed Changes

Copilot reviewed 19 out of 21 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/api/*	New API module with handlers, models, and health check endpoint
src/services/mod.rs	Refactored MessageService to use Arc and return Message objects
src/storage/traits.rs	Added Send + Sync bounds to Storage trait for thread safety
src/main.rs	Updated to run Axum web server instead of simple CLI
tests/*	Comprehensive integration test suite for all API endpoints
Cargo.toml	Added web framework and testing dependencies

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