feat(data-loader): add getClaudePaths function for multiple path support

- Add getClaudePaths() function to support multiple Claude data directories

- Support environment variable (comma-separated paths)

- Support both new default (~/.config/claude) and old default (~/.claude)

- Implement path normalization and duplicate removal

- Update data loading functions to use multiple paths

- Maintain backward compatibility with getDefaultClaudePath()

Author: ryoppippi