feat: introduce plugin-based notifier system and refactor core

[kaedeek]

Overview

This PR introduces a plugin-based architecture and removes direct dependencies on external notification libraries.

Changes

• Removed node-notifier from core to improve security and reduce dependencies
• Added setNotifier() API to allow external notification plugins
• Refactored logging output to use process.stdout.write for better performance
• Improved module exports for better TypeScript / ESM compatibility
• Cleaned up unused dependencies

Breaking Changes

• Removed built-in notification support (node-notifier)
• Users must now provide a notifier via plugin if needed

Example

import VersaLog from "versalog"
import { notifyPlugin } from "versalog/plugin/notify"

const log = new VersaLog()
notifyPlugin(log)

log.error("Test error")

Motivation

• Resolve indirect dependency vulnerabilities (uuid via node-notifier)
• Reduce bundle size and improve maintainability
• Provide a more flexible and extensible architecture

Notes

This is a breaking change, so version bump to v2.1.0 is recommended.