feat: implement request/response pattern over Kafka

[mcollina]

Summary

• Implement HTTP request/response routing through Kafka topics
• Add correlation ID handling for request matching with automatic UUID generation
• Support configurable timeouts (default 30 seconds) with proper error handling
• Enable custom HTTP status codes in responses via x-status-code header
• Preserve all HTTP headers in Kafka messages for full context passing

Features Added

Core Request/Response Flow

• HTTP Endpoints: Configure custom paths that route through Kafka topics
• Correlation Tracking: Automatic correlation ID generation and matching
• Timeout Handling: Configurable timeouts prevent hanging requests
• Status Code Support: Response messages can include HTTP status codes

Configuration

New requestResponse array in kafka config:

{
  "requestResponse": [
    {
      "path": "/api/process",
      "requestTopic": "request-topic", 
      "responseTopic": "response-topic",
      "timeout": 5000
    }
  ]
}

Enhanced Header Processing

• All HTTP headers are now preserved in Kafka messages
• Correlation ID automatically added to request messages
• Response headers properly forwarded to HTTP response

Usage Example

HTTP Request:

curl -X POST http://localhost:3042/api/process \
  -H "Content-Type: application/json" \
  -d '{"data": "request payload"}'

Flow:

1. Request published to request-topic with correlation ID
2. External service processes request and publishes response to response-topic
3. Response automatically routed back to original HTTP caller
4. HTTP request completes with response data

Test Coverage

• ✅ Successful request/response round-trip
• ✅ Timeout handling when no response received
• ✅ Correlation ID generation and matching
• ✅ HTTP status code propagation
• ✅ Header preservation
• ✅ Schema validation

Backward Compatibility

Fully backward compatible - existing functionality unchanged.

🤖 Generated with Claude Code

Fixes #2

[ShogunPanda]

This is wrong. 4xx are client errors, but here we're returning a server error. I would use 500, 503 or 504.

[mcollina]

@ShogunPanda PTAL

[ShogunPanda]

LGTM!