Extract logging to pkg/log for use outside CLI:
- Logger with Debug/Info/Warn/Error levels
- Key-value pairs for structured logging
- Customisable styling and output
- Optional Core framework integration via Service
Enhance pkg/errors with:
- Wrap() and WrapCode() helpers
- Code() for error codes
- Op(), ErrCode(), Message(), Root() extractors
- Standard library wrappers (Is, As, New, Join)
Update pkg/cli/log.go to use pkg/log with CLI styling.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
