0.3

Add multi-profile and AWS shared config support to s3cmd-style config

handling

- Support multiple profiles/sections in .s3cfg and use
  --profile/AWS_PROFILE to select
- Implement config file resolution order: ./ .s3cfg, ~/.s3cfg, explicit
  --config
- Add fallback to AWS shared config (~/.aws/config, ~/.aws/credentials)
  when creds missing
- Introduce --endpoint and --region flags with environment variable
  support
- Enforce path-style addressing and custom endpoint normalization in AWS
  session
- Remove reflection-based config parsing, apply explicit CLI/env
  overrides
- Improve verbose output for effective configuration and session details