- Add multi-segment namespace support to ARN parsing
- Refactor permission checking to use map lookup
- Wrap lookup errors with ErrNotFound in filer operations
- Standardize splitPath to use path package
- Move ARN parsing, path helpers, and metadata structures to utils.go
- Extract all extended attribute and filer operations to filer_ops.go
- Reduces code duplication and improves modularity
- Improves code organization and maintainability