Add comprehensive setup and synchronization documentation

[KimboPulus]

Overview

The Custom-taskbar-timer-app currently lacks comprehensive documentation for users wanting to set up and configure the synchronization between desktop (Electron) and mobile (React Native) versions.

Problem

New users may struggle to:

• Understand the initial setup process for both desktop and mobile apps
• Configure the taskbar timer synchronization between platforms
• Troubleshoot common sync issues

Proposed Solution

Create detailed documentation that includes:

• Setup Guide: Step-by-step instructions for installing and configuring both the Electron desktop app and React Native mobile app
• Synchronization Guide: How to enable, configure, and manage real-time sync between devices
• Shortcuts Reference: Comprehensive list of keyboard shortcuts and their mobile equivalents
• Troubleshooting: Common issues and their solutions
• Architecture Overview: High-level explanation of how the sync mechanism works

Deliverables

• README.md enhancements
• docs/ folder with detailed guides
• Sync troubleshooting guide
• Quick start guide for new users

This will significantly improve the user experience and reduce support questions.