Automate recurring notification for SDK releases pending approval

## Summary
Implement automated recurring email notifications for SDK releases that remain pending approval for more than 24 hours.

## Goal
Ensure release stakeholders are reminded when an auto SDK release is waiting on approval too long, reducing the chance of stalled releases.

## Audience
- Release plan owner
- SDK code owner
- Shanghai SDK team
- azsdk engagement exp support

## Requirements
- Detect when an SDK release is in pending approval state for more than 24 hours.
- Send an automated email notification once the 24-hour threshold is crossed.
- Continue sending the notification on a weekly recurring cadence while the release remains pending approval.
- Stop recurring notifications once the release is either released or abandoned.
- Include enough release context in the email for recipients to quickly identify the blocked approval.
- Avoid duplicate notifications outside the defined weekly recurrence.

## Suggested Acceptance Criteria
- Notification is triggered only for releases pending approval longer than 24 hours.
- Weekly recurring notifications continue until release completion or abandonment.
- Recipient resolution includes the intended audience.
- Notification lifecycle ends automatically when the release leaves pending approval.
- Logging, scheduling, and retry behavior are defined.

## Notes
This sub-issue covers the delayed and recurring notification flow for SDK release approval.