Add structured request logging and trace propagation for backend observability

**Is your feature request related to a problem? Please describe.**

Backend logs currently have limited request-level context, making it more difficult to correlate application events, troubleshoot issues, and trace requests across services.

**Describe the solution you'd like**

Introduce structured request logging and request correlation support by:

* Adding a Django request logging middleware.
* Capturing request metadata such as:

* request_id
* trace_id
* request method
* request path
* service
* environment
* Adding a logging filter to inject request context into log records.
* Outputting logs in structured JSON format.
* Propagating identifiers back to clients through:

* `X-Request-ID`
* `X-Trace-ID`

**Describe alternatives you've considered**

An alternative would be relying solely on external observability tooling. However, adding request context directly into application logs provides immediate value and improves compatibility with centralized logging and monitoring platforms.

**Are you going to work on implementing this?**

* [x] Yes

**Additional context**

A working implementation has already been prepared and tested on a fork.

Files involved:

* backend/apps/common/middlewares/request_logging.py
* backend/settings/base.py

The implementation supports request correlation, structured logging, and trace propagation, which aligns with observability and monitoring goals.