Feature Request: Automatically Retry Adding Failed Installations After Key Package Issues

[mchenani]

Is your feature request related to a problem?

Right now, when we try to add a member and their installation has a missing, empty, or expired key package, we soft-fail and save their installation ID under FailedInstallations in the Intents and Welcome messages. The problem is: even if they fix the issue and upload a fresh key package, we never try adding them again automatically.
related to:
#1507
#1606

Describe the solution to the problem

Implement a retry mechanism to automatically reattempt adding previously failed installations. Specifically:

• Periodically check installations listed under FailedInstallations for a valid key package.
• If a healthy key package is detected, proceed to add the member automatically.

This solution ensures that members who resolve their key-package issues are added without manual intervention.

Describe the uses cases for the feature

No response

Additional details

No response