feat: Add CancellationToken support to AWS S3 methods

[thomhurst]

Summary

• Adds CancellationToken cancellationToken = default parameter to all S3 bucket operation methods
• Propagates cancellation tokens to AWS SDK async calls
• Adds ConfigureAwait(false) for consistent async behavior

Why

Previously, S3 operations could not be cancelled - if a pipeline was cancelled, in-flight AWS API calls would continue until completion. This change allows proper cancellation propagation.

Backward Compatibility

All methods use CancellationToken cancellationToken = default, so existing code without cancellation tokens will continue to work without modification.

Test plan

• Build succeeds
• CI pipeline passes

Fixes #1544

🤖 Generated with Claude Code

[thomhurst]

Summary

Adds CancellationToken support and ConfigureAwait(false) to all AWS S3 bucket operation methods.

Critical Issues

None found ✅

Suggestions

Consistency across AWS services: The Lambda.cs class in the same package doesn't expose any async methods yet, but if similar wrapper methods are added to other AWS service classes (Lambda, etc.) in the future, they should follow this same pattern of accepting CancellationToken and using ConfigureAwait(false).

Pattern verification: The changes correctly follow the established patterns in the codebase:

• ✅ CancellationToken parameter with default value (consistent with src/ModularPipelines/Http/Http.cs:32)
• ✅ ConfigureAwait(false) usage (consistent with src/ModularPipelines/Http/Http.cs:36, 41, 48)
• ✅ Proper async propagation to underlying AWS SDK calls

Verdict

✅ APPROVE - No critical issues

The implementation correctly addresses issue #1544 by enabling cancellation support while maintaining backward compatibility. The pattern is consistent with the rest of the codebase.

[Copilot]

Pull request overview

This PR adds proper cancellation support to AWS S3 bucket operations by introducing CancellationToken parameters and applying ConfigureAwait(false) for consistent async behavior. This allows S3 operations to be cancelled when a pipeline is cancelled, preventing in-flight AWS API calls from continuing unnecessarily.

• Adds CancellationToken cancellationToken = default to all 16 S3 method signatures
• Propagates cancellation tokens to AWS SDK async method calls
• Adds ConfigureAwait(false) to all async operations for consistent async patterns