feat: add S3/object storage bucket upload support

Summary

This merge request adds S3/object storage bucket upload support to Corpus CLI, allowing users to upload files directly from s3:// URIs.

Changes

S3/Object Storage Integration

• Add aioboto3 and botocore dependencies for S3 integration
• Implement S3 download producer for s3:// URI support
• Add S3 credential management and interactive credential setup
• Add ProgressTracker for upload progress monitoring
• Add S3 buffer management and cleanup utilities
• Update CLI to accept s3:// URIs in upload command
• Add comprehensive test coverage for S3 upload functionality

Upload Fixes

• Fix macOS buffer cleanup: delete .DS_Store before rmdir, use shutil.rmtree for final cleanup instead of os.rmdir

Testing

• Added comprehensive test coverage for S3 upload functionality
• Fixed mypy type errors and ruff linting issues
• Updated existing tests to match new code paths