feat(logging): Implement robust Zap logger initialization

[nutcas3]

This commit introduces a new logging package designed to provide a centralized and configurable logging solution using go.uber.org/zap. This setup ensures consistent logging practices across the application, with support for different logging levels, development/production configurations, and structured output.

Key features and components:

• Global Logger Instance:
  • Uses a sync.Once (or in this case, a sync.RWMutex with an initialized flag)
    to ensure the zap.Logger is initialized only once, providing a singleton
    instance accessible throughout the application.
• Configurable Logging:
  • LogLevel enum: Defines debug, info, warn, and error levels.
  • Config struct: Allows specifying Level, Development mode, and Encoding
    (e.g., "json" or "console").
  • DefaultConfig(): Provides a sensible default configuration (info level,
    production mode, JSON encoding).
• Initialize(config Config) Function:
  • Sets up the zap.Logger based on the provided Config.
  • Dynamically sets zapcore.Level based on LogLevel.
  • Configures zap.Config for development (human-readable) or production (JSON,
    ISO8601 timestamps) encoder settings.
  • Sets OutputPaths to stdout and ErrorOutputPaths to stderr.
  • Handles potential errors during logger build process.
• Logger() Function:
  • Provides global access to the initialized *zap.Logger instance.
  • Includes ensureInitialized() to lazily initialize the logger with default
    settings if Initialize hasn't been explicitly called.
• Convenience Functions:
  • With(fields ...zap.Field): Allows adding contextual fields to the logger.
  • Debug, Info, Warn, Error: Simple wrappers for common logging levels.
• Sync() Function:
  • Flushes any buffered log entries, important for graceful shutdowns to prevent
    lost logs.

This logging package significantly enhances the observability and debugging capabilities of the application by providing a robust, flexible, and easy-to-use logging utility.