refactor: replace zap with pluggable Logger interface

[rjasonadams]

• Introduce minimal Logger interface with no external dependencies
• Add NoOpLogger as default implementation
• Replace *zap.Logger with Logger interface in reader and writer
• Remove all zapcore.ObjectEncoder dependencies
• Add String() methods to seekTableDescriptor, seekTableFooter, seekTableEntry, and FrameOffsetEntry for clean logging output
• Use WithRLogger/WithWLogger for consistency
• Include examples showing how to implement custom loggers (including zap adapter)
• Successfully remove go.uber.org/zap dependency from pkg module

This change allows users to integrate any logging library while keeping the package dependency-free for logging.