Added automated_email_recipients database table

[cmraible]

ref https://linear.app/ghost/issue/NY-936

Summary

• Adds automated_email_recipients table to track automated emails sent to members
• First step in implementing welcome emails in the member activity feed
• Follows the email_recipients pattern: no FK on member_id to preserve audit history when members are deleted

[github-actions]

It looks like this PR contains a migration 👀
Here's the checklist for reviewing migrations:

General requirements

• ⚠️ Tested performance on staging database servers, as performance on local machines is not comparable to a production environment
• Satisfies idempotency requirement (both up() and down())
• Does not reference models
• Filename is in the correct format (and correctly ordered)
• Targets the next minor version
• All code paths have appropriate log messages
• Uses the correct utils
• Contains a minimal changeset
• Does not mix DDL/DML operations
• Tested in MySQL and SQLite

Schema changes

• Both schema change and related migration have been implemented
• For index changes: has been performance tested for large tables
• For new tables/columns: fields use the appropriate predefined field lengths
• For new tables/columns: field names follow the appropriate conventions
• Does not drop a non-alpha table outside of a major version

Data changes

• Mass updates/inserts are batched appropriately
• Does not loop over large tables/datasets
• Defends against missing or invalid data
• For settings updates: follows the appropriate guidelines

[coderabbitai]

Walkthrough

This pull request introduces a new database table automated_email_recipients to the system. The changes include a migration file to create the table with a defined schema (id, automated_email_id, member_id, member_uuid, member_email, member_name, created_at, updated_at), schema definitions in the core schema configuration, updates to backup and export table lists to include the new table, and corresponding test updates to reflect the schema changes and expected exported tables.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding the automated_email_recipients database table, which is the primary objective of this PR.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description check	✅ Passed	The PR description accurately describes the changeset: adding an automated_email_recipients table to track automated emails sent to members.

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✨ Finishing touches

• 📝 Generate docstrings

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[troyciesco]

marking as request changes bc i think we want to do the two things i noted but lmk if i'm wrong!