feat: implement s3 dump extension

[jaronoff97]

No description provided.

[macroscopeapp]

Approvability

Verdict: Needs human review

This PR introduces a new S3 dump extension feature with significant new runtime behavior including background flush tasks, extension sink wiring through log processing, and new configuration types. Additionally, an unresolved comment identifies that temporary IAM credentials (Lambda/ECS/EKS) won't work due to missing AWS_SESSION_TOKEN handling. New features of this scope warrant human review.

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