refactor: remove claudeCodeEnv option and update environment variable…

[cuipengfei]

… handling

[Copilot]

Pull Request Overview

This PR removes the claudeCodeEnv option from the command line interface and simplifies environment variable handling for Claude Code integration. The refactoring eliminates a conditional flag that was enabled by default and always generates the full set of environment variables when Claude Code is requested.

• Removed the claudeCodeEnv boolean option from the CLI interface
• Added additional environment variables for Claude Code configuration
• Updated documentation to reflect the new environment variable set

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/start.ts	Removed claudeCodeEnv option from interface and CLI, simplified conditional logic, and added new environment variables
README.md	Removed documentation for the --claude-code-env flag and updated example configuration with new environment variables

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