What is Changed / Added

• Migrated the file upload and download integrations to the new SDK promise-based contract, removing the old completion callback flow.
• Refactored temporal file uploads to use async/await, propagate abortSignal, keep the same progress/start/finish/error events, and ensure streams are closed on abort or failure.
• Refactored storage file downloads to use the new direct promise flow, preserve progress and lifecycle events, and replace manual stop-state handling with AbortController.
• Simplified the download factory by passing the Environment instance directly to the downloader instead of wrapping the SDK call in an additional adapter layer.
• Refactored thumbnail uploads to use an abortable timeout, so timed out uploads are actively cancelled and timers are always cleaned up.
• Refactored backup content uploads to call environment.upload directly, rely on the SDK for multipart handling, propagate abortSignal, and preserve stream cleanup and existing error mapping behavior.
• Updated the related tests to match the new SDK behavior, including success, timeout, abort, empty contentsId, and failure scenarios.

Why

• The SDK contract changed and now resolves uploads and downloads directly through promises, so the previous callback-based implementation no longer matched the actual runtime behavior.
• The previous flow tied cleanup logic to callback completion paths, which made stream and listener handling more fragile after the SDK migration.
• Using async/await with explicit abort propagation makes the code easier to read, easier to reason about, and safer to maintain.
• Cancelling transfers on timeout or abort prevents leaving streams, listeners, or background operations alive after the caller has already considered the operation failed.
• Removing unnecessary local multipart handling and compatibility wrappers keeps the integration closer to the SDK contract and reduces maintenance overhead.