Added request ID contract and tracing developer guide #573

[Apoorv-Raj777]

Related Issues

Closes #573

Description

This PR introduces comprehensive contributor-facing documentation for the request ID tracing contract in SecuScan. The documentation explains how request IDs are generated (via ContextVar and uuid4), how they pass through middleware (RequestIDMiddleware), how they correlate across application logs (using JSONFormatter), and how they are stored within database audit logs (audit_log table JSON context). Additionally, developer-facing guidelines on background task propagation and end-to-end debugging guides are provided. Links to the documentation have also been integrated into relevant development guides and source files.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

• Verified that all paths and linked code references in the documentation match the implemented behavior in the codebase.
• Ran Python syntax validation (py_compile) on the updated backend/secuscan/request_middleware.py middleware file to ensure no syntax issues were introduced.
• Reviewed markdown rendering of links and contents.

Checklist

• My code follows the code style of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.