Translate Chinese comments and messages to English in mise Java integration script

[Copilot]

Addresses feedback from PR #24 to internationalize the mise_java_home_integration.sh script by replacing Chinese text with English throughout.

Changes

• Comments: Translated inline comments explaining logic and section headers
• Error messages: Converted all error output (e.g., "错误: 未找到 mise 命令" → "Error: mise command not found")
• User prompts: Changed interactive confirmations and informational messages to English
• Usage instructions: Translated help text in the argument parsing section

Example:

# Before
echo "❌ 错误: 当前目录没有激活任何 Mise Java 版本。"
echo "💡 请先执行: mise use java@21 (或你想要的版本)"

# After
echo "❌ Error: No Mise Java version is active in the current directory."
echo "💡 Please run: mise use java@21 (or your desired version)"

Script functionality unchanged.

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[paigeman]

LGTM