Process email with ForestMQ background jobs

## Summary
Handle email delivery through ForestMQ background jobs.

## Context
Use ForestMQ and its Python client to process email jobs asynchronously rather than sending email inline from platform request handlers.

## Scope
- Define email job payloads and queue names.
- Integrate platform code with ForestMQ for enqueueing email jobs.
- Use the ForestMQ Python client for the worker that processes email jobs.
- Select/configure the email provider separately from queue mechanics.
- Add retry, failure logging, and idempotency strategy.
- Cover initial email types such as account/admin emails and storefront-related notifications.

## Acceptance Criteria
- Platform can enqueue email jobs to ForestMQ.
- A Python worker can consume and process email jobs.
- Failed jobs are logged and retry behavior is defined.
- Email provider configuration is documented.
- Sending email does not block user-facing requests.

The issue names platform request handlers, ForestMQ integration, and a Python worker, but no repository files or tests. Start by locating the request-handler and worker entry points, then define the queue and email-job design; done means asynchronous enqueueing and consumption, documented provider configuration, and specified retry, failure logging, and idempotency behavior.

Written by the indexing model from the issue text.