Build subscription pause/resume with billing adjustment

[Smartdevs17]

Context

Subscriptions need pause/resume capability.

Current Limitation

Subscriptions can only be cancelled.

Expected Outcome

• Pause/resume functionality
• Billing adjustment
• Pause analytics
• Pause notifications

Acceptance Criteria

• Subscription pause with duration
• Billing adjustment for pause
• Resume with billing restart
• Pause analytics
• Pause notifications
• Pause limits
• Pause documentation