…o 0.15.1

Bug Fix:
- **QoS 1 Publish Reliability**: Fixed error handling in QoS 1 message processing
- **Resource Leak Prevention**: Ensure inflight messages are properly cleaned up on errors
- **Ordering Guarantee**: Maintain proper ACK sequencing even after publish failures

Key Changes:
1. **Error Handling Improvement**:
   - Added proper error mapping to clean up inflight messages on publish failure
   - Separated publish operation from ACK sending for better error isolation
   - Ensured inflight removal happens before propagating errors

2. **Version Bump**:
   - Bumped workspace version from 0.15.0 to 0.15.1
   - Updated all plugin dependencies to 0.15.1
   - Maintained version synchronization across all components

Technical Details:
- The fix addresses a potential resource leak where inflight messages wouldn't be cleaned up if `self.publish()` failed
- Now properly removes the inflight entry before returning the error
- Maintains the ACK sending operation separately to ensure proper protocol sequencing

This patch release (0.15.1) focuses on improving reliability and preventing resource leaks in QoS 1 message handling.

- Replaced `map_err` with `inspect_err` for cleaner error side effects
- Maintains same functionality: removes inflight entry on publish failure
- More idiomatic Rust error handling pattern
- Keeps original error unchanged while performing cleanup

chore: bump version to 0.15.1 and improve shutdown process