feat(s3,utils): use niquests on_upload hook and optimize stream chunking

[Andarius]

• Split get_stream_chunk into get_stream_chunk (bytes, uses bytearray internally) and get_stream_chunk_str, removing 5 redundant helper functions
• Replace on_chunk_received with niquests on_upload hook in s3_put_object, s3_multipart_upload, and s3_file_upload for fine-grained byte-level upload progress
• Make S3Session fields (endpoint_url, access_key, secret_key, region) optional, falling back to botocore defaults
• Widen s3_put_object and upload_part to accept bytes | bytearray

Summary by CodeRabbit

• New Features

  • S3 session configuration now supports optional credentials for flexible deployment scenarios
  • S3 upload operations expanded to accept additional data types
  • Enhanced upload progress tracking mechanism

• Tests

  • Comprehensive test coverage added for stream processing with multiple scenarios

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 8463e30 and c918ec1.

⛔ Files ignored due to path filters (1)

• uv.lock is excluded by !**/*.lock

📒 Files selected for processing (4)

• tests/s3/test_niquests.py
• tests/test_utils.py
• tracktolib/s3/niquests.py
• tracktolib/utils.py

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Walkthrough

The pull request refactors the upload callback mechanism from on_chunk_received to on_upload (accepting PreparedRequest), makes S3Session configuration fields optional with defaults, and separates stream chunking into distinct paths for bytes and strings with a new BytesBuffer utility class.

Changes

Cohort / File(s)	Summary
Test Suite Updates tests/s3/test_niquests.py, tests/test_utils.py	Updated S3 test to use new on_upload callback signature and replaced received_size assertions with upload_progress_called flag. Added parametric test_get_stream_chunk_str function with three test scenarios for string chunking.
S3 Upload Module tracktolib/s3/niquests.py	Introduced OnUpload type alias; made S3Session fields (endpoint_url, access_key, secret_key, region) optional with None defaults; guarded credential setup; extended function signatures to accept `bytes
Stream Utilities tracktolib/utils.py	Renamed previous generic get_stream_chunk to get_stream_chunk_str for string streams; created new get_stream_chunk for bytes streams using AsyncIterable[bytes]; introduced BytesBuffer class with put, get, get_all methods for efficient bytes accumulation; expanded imports to include collections and io.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/s3-upload-progress-and-stream-chunk-cleanup

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