feat: add JSON logging and `correlationId` for requests

[astewayn17]

Description

Configure the backend to emit JSON logs suitable for tools like Splunk, and ensure each HTTP request has a correlationId for tracing.

Acceptance Criteria

Scenario: Add structured logging with correlation tracking

Given I am implementing observability for the backend application
When I configure JSON logging and add correlation ID tracking to requests
Then the application logs should be in JSON format with correlationId included
And logs for file uploads should clearly show the lifecycle of a single request
And it should be possible to grep logs by correlationId and see related events
And all changes should be committed and pushed to GitHub