Add request size limit to prevent DOS attacks

[volcodes]

To mitigate the risk of Denial-of-Service (DoS) attacks, implement a request size limit for the Go application. This will ensure that excessively large payloads are rejected, protecting the application from resource exhaustion.

Acceptance Criteria:

• Set a maximum request size limit (e.g., 1 MB) for incoming HTTP requests.
• Update the application to reject requests exceeding the size limit with an appropriate HTTP response (e.g., 413 Payload Too Large).
• Log rejected requests for monitoring and debugging purposes.
• Write unit tests to validate the request size limit functionality.
• Ensure existing workflows are unaffected by the new limit.

Technical Notes:

• Use the http.MaxBytesReader function or middleware to enforce the request size limit.
• Consider configuring the limit as an environment variable for flexibility.
• Follow existing logging conventions for consistency.
• Ensure the response includes clear information about the size limit for client reference.

Priority: High
Labels: Security, Backend, DoS Mitigation, Go