- Update CHANGELOG.md for v0.4.0 - Update Makefile FALLBACK_VERSION to 0.4.0 - Fix lint warnings (godoc comments, goconst) - Clean up code formatting
- Add atomic EWMA Stats field to Target - Implement LeastTime balancer with header_time and last_byte metrics - Support Select and SelectExcluding with zero-lock design - Add ResponseTimeRecorder interface for proxy integration