Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@crates/lib/src/storage/s3.rs`:
- Line 186: The multipart upload currently hardcodes PART_SIZE = 8 * 1024 * 1024
and increments part_num in the upload loop; add a guard to prevent exceeding
S3's 10,000-part limit by either (a) checking the reader/content length up front
(if available) and computing a larger PART_SIZE so total_parts <= 10_000, or (b)
if length is unknown, detect in the upload loop (where part_num is incremented)
and return a clear error when part_num > 10_000. Update the multipart upload
function that defines PART_SIZE and uses part_num to perform this validation and
return an error early instead of continuing to stream.
- Around line 238-336: The spawned upload_task (JoinHandle named upload_task)
can continue issuing upload_part calls after the producer errors and before
abort_multipart_upload runs; ensure the worker is explicitly cancelled and
awaited before calling abort_multipart_upload: on any early return/error in the
producer/result block, call upload_task.abort() (or send a cancellation signal
via tx/closure), then await upload_task (handle the JoinError) to guarantee all
in-flight part uploads stop/complete before invoking
client.abort_multipart_upload(); update the error paths around the producer loop
and the Result handling where upload_task is dropped so upload_task.abort() and
upload_task.await are executed prior to calling abort_multipart_upload.

---

Nitpick comments:
In `@crates/lib/src/error.rs`:
- Around line 150-151: The AwsSdkError enum variant currently wraps the AWS
error but doesn't expose it as the source for Error::source(); update the
AwsSdkError variant in the error enum (the AwsSdkError(...) variant in error.rs)
to mark the inner boxed error as the source (either by adding the #[source]
attribute to the variant or by renaming the inner field to source) so thiserror
will wire through the underlying AWS error chain; keep the existing #[error("AWS
SDK error: {0}")] display message while adding the source annotation to preserve
error chaining.

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@crates/lib/src/storage/s3.rs`:
- Line 185: The build fails because ByteStream::from_body_1_x (used in
storage::s3.rs) requires the aws-sdk-s3 crate to enable the http-body-1-x
feature; update Cargo.toml to change the aws-sdk-s3 dependency to include
features = ["http-body-1-x"] (e.g. aws-sdk-s3 = { version = "1.127.0", features
= ["http-body-1-x"] }) and then run cargo build/cargo update to ensure the
feature is picked up.