Implement Unified Error Handling System for Tauri Backend and React Frontend

## Description
Create a unified error handling system that works seamlessly between the Tauri Rust backend and React frontend, utilizing serde serialization for consistent error communication across the application boundary.

## User Story
As a developer working on the Developers Utility application, I want a standardized error handling system so that errors from the Rust backend can be properly serialized, transmitted, and handled in the React frontend with consistent structure and meaningful error information.

## Problem Statement
Currently, error handling between the Tauri backend and React frontend lacks consistency, making it difficult to:
- Provide meaningful error messages to users
- Debug issues across the Rust/TypeScript boundary
- Maintain consistent error handling patterns
- Properly serialize complex error types

## Technical Requirements

### Backend (Rust/Tauri)
- [ ] Create a unified `AppError` enum that covers all possible error types
- [ ] Implement `serde::Serialize` and `serde::Deserialize` for error types
- [ ] Follow Tauri's error handling best practices
- [ ] Support error chaining and context
- [ ] Include error codes for programmatic handling

### Frontend (React/TypeScript)
- [ ] Create corresponding TypeScript interfaces for error types
- [ ] Implement error boundary components
- [ ] Create utility functions for error handling
- [ ] Provide user-friendly error messages

### Integration
- [ ] Ensure seamless serialization/deserialization across the boundary
- [ ] Maintain error context and stack traces where possible
- [ ] Support both synchronous and asynchronous error handling