Add FTP Capacity Block Expiration Notification Feature

[jatinkulkarni]

Issue

Description of Changes

Implements FTP Capacity Block Expiration Notification feature for SageMaker extension. Adds three-tier notification system (30min, 10min, 2min warnings) to alert users before capacity block expiration, preventing unexpected data loss.

Key additions:

• capacityBlockWarning.ts - notification display logic
• constant.ts - CB notification constants and metadata interfaces
• extension.ts - monitoring initialization, scheduling, cleanup
• sagemaker.series - patch file registration

Technical highlights:

• Handles setTimeout limits for long-duration blocks (>24 days) via 7-day periodic rechecks
• Auto-reschedules if capacity block extended (1min tolerance)
• Accounts for EC2's 30min shutdown window
• Toast notifications at 30/10min, modal at 2min with "Save All" option

Testing

Tested via GitHub Actions workflow on feature branch with DISABLE_MANGLE=true. Build artifacts generated successfully. Verified notification scheduling logic and timeout handling.

Screenshots/Videos

Additional Notes

Changes limited to SageMaker-specific directories (patches/sagemaker/), enabling SageMaker team self-approval per CODEOWNERS. Feature enhances UX by preventing data loss during capacity block expiration with defensive error handling and graceful degradation.

Backporting

Consider backporting to supported version branches (1.0.x, 1.1.x) if needed for existing SageMaker deployments.

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[arkaprava08]

Please remove hardcoded contants and read from env variables or atleast fall back to. This would make the IDE logic very rigid

[arkaprava08]

Why can't we move under sagemaker-extension rather than creating a new one? Also can we make the client side logic generic while pushing the notifications from backend?