Add independent log level control for stderr and OTLP loggers.
Both can be configured via environment variables or programmatically
at runtime.
- Add SetLevel() and SetOTLPLevel() for runtime control
- Add ParseLevel() to convert strings to slog.Level
- Support LOG_LEVEL and OTLP_LOG_LEVEL env vars
- Maintain backward compatibility with DEBUG env var
- Add comprehensive test coverage
Ask Bjørn Hansen
66b51df2af