Add comprehensive Unicode handling guide and UTF-8 encoding configuration

[Copilot]

Overview

This PR adds comprehensive documentation and configuration for Unicode handling across multiple programming languages, addressing the need for consistent UTF-8 encoding standards and multi-language string processing best practices.

Problem Statement

The repository needed guidance on:

• 原始碼編碼 (Source Code Encoding): Standardizing on UTF-8 to prevent mojibake (乱码)
• 字串與 Unicode (String & Unicode): Understanding language-specific differences in string handling
• 比對與正規化 (Comparison & Normalization): Proper Unicode equivalence comparison techniques
• 資料結構 (Data Structures): Multi-language localization patterns

Solution

1. Unicode Handling Guide (UNICODE_HANDLING_GUIDE.md)

Created a comprehensive 662-line guide covering:

Source Code Encoding

• UTF-8 as project standard
• Editor configuration examples for VS Code, JetBrains IDEs, and Vim

Language-Specific String Handling

• Python 3: str as Unicode with normalization examples
• Rust: String/&str as guaranteed valid UTF-8
• Go: string as byte sequence, conventionally UTF-8
• JavaScript/TypeScript: string as UTF-16 with surrogate pair warnings
• C# / .NET: string as UTF-16 with StringInfo usage

Unicode Normalization

• Detailed explanation of NFC, NFD, NFKC, NFKD forms
• Safe comparison examples for all languages
• Practical demonstrations with composed/decomposed characters (café vs café)

Multi-Language Data Structures

• Dictionary<Locale, TokenMap> pattern implementation
• Complete examples in TypeScript, Python, Rust, Go, and C#
• Includes Chinese (你好), Japanese (こんにちは), and English translations

2. Project Configuration

.gitattributes

• Enforces UTF-8 encoding for source files
• Sets proper line endings and text normalization
• Ensures consistent handling across platforms

.editorconfig

• Enforces UTF-8 charset across all file types
• Configures consistent indentation per language
• Provides uniform coding style across different editors

3. Enhanced README

Updated with:

• Quick reference table comparing string handling across languages
• Key considerations for Unicode processing
• Direct link to comprehensive guide

Examples

The guide includes working code examples that demonstrate proper Unicode handling:

# Python: Unicode normalization for comparison
from unicodedata import normalize
composed = "café"
decomposed = "café"
print(normalize('NFC', composed) == normalize('NFC', decomposed))  # True

// JavaScript: Handling emojis and surrogate pairs
const emoji = "🌍";
console.log(emoji.length);        // 2 (surrogate pair)
console.log([...emoji].length);   // 1 (one code point)

// Rust: Safe UTF-8 handling
let text = "Hello 世界 🌍";
println!("Byte length: {}", text.len());
println!("Char count: {}", text.chars().count());

Testing

All files verified to:

• Use UTF-8 encoding (file -i confirms charset=utf-8)
• Contain multi-language Unicode characters (Chinese, Japanese, emojis)
• Render correctly across different platforms

Benefits

✅ Prevents encoding issues: UTF-8 configuration prevents mojibake
✅ Cross-platform consistency: Works across Windows, macOS, and Linux
✅ Language coverage: Supports Python, Rust, Go, JavaScript/TypeScript, and C#
✅ Practical guidance: Copy-paste ready examples for immediate use
✅ Best practices: Comprehensive recommendations for Unicode handling

Related

Addresses requirements from issue regarding Unicode handling best practices across different programming languages.

Original prompt

ChatGPT: " * 原始碼編碼：專案統一 UTF-8；檔案另存為 UTF-8 可避免亂碼（多數現代編譯器/工具預設支援）。

• 字串與 Unicode（語言差異大要留意）：

  • Python 3 的 str 為 Unicode；
  • Rust String/&str 為 UTF-8；
  • Go 的 string 是位元組序列，慣例存放 UTF-8；
  • JS/TS 與 .NET/C# 的 string 以 UTF-16 編碼單位運作（遇到表情符號/合字需留心 code point vs. code unit）。

• 比對與正規化：若要做「等價比對」（如「é」的合成/分解形），請考慮使用 ICU 或語言內建的 Unicode Normalization API。

• 資料結構：若多語系，常見結構是 Dictionary<string, TokenMap>，例如 locale -> (token -> localized text)。"

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