XDG Base Directory Support

Claude Code now follows the XDG Base Directory specification for better organization of files:

• State files: $XDG_STATE_HOME/claude/ (defaults to ~/.local/state/claude/)
• Cache files: $XDG_CACHE_HOME/claude/ (defaults to ~/.cache/claude/)
• Data files: $XDG_DATA_HOME/claude/ (defaults to ~/.local/share/claude/)
• Executables: ~/.local/bin/claude

The application will automatically migrate existing files from the old location (~/.claude/) to the new XDG-compliant locations on first run.