Add login token command to save API token to config file

[scottlovegrove]

Summary

• Adds tw login token <TOKEN> command that saves API tokens to ~/.config/twist-cli/config.json
• Cross-platform support using existing config system with proper directory creation
• Simple implementation with token validation (minimum 10 characters)
• Comprehensive test coverage with 4 test cases including success, error handling, token trimming, and help

Changes

• src/lib/auth.ts: Added saveApiToken() function using existing config system
• src/commands/login.ts: New login command group with token subcommand
• src/index.ts: Registered new login command in main entry point
• src/tests/login.test.ts: Comprehensive test coverage for all functionality

Usage

# Save API token
tw login token your_api_token_here

# Show help
tw login --help
tw login token --help

Test plan

• TypeScript compilation passes
• All tests pass (84/84 total)
• Manual testing verified:
  • Help system works correctly
  • Token saving creates proper config file at ~/.config/twist-cli/config.json
  • Config directory auto-creation works
  • Token validation works (rejects < 10 characters)
  • Existing config preservation works

🤖 Generated with Claude Code

[gnapse]

Updated the README to document the new tw login token command in the Setup section. Thanks!

[github-actions]

🎉 This PR is included in version 1.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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