[Code Review][Nice-to-have] No macOS support

## Context
Source: https://github.com/mgradwohl/tasksmack/blob/main/CODE_REVIEW_ISSUES.md

**Priority:** Nice-to-have

**Area:** Cross-Platform Issues

## Details
**Category:** Platform Support

**Problem:**
README mentions cross-platform but only Linux and Windows are implemented.

**Recommendation:**
Either:
1. Add macOS implementations (if target platform), or
2. Update docs to clearly state "Linux and Windows only"

Start with CODE_REVIEW_ISSUES.md and the README to verify the current platform claim and the Linux and Windows support described there. First resolve whether macOS is a target platform; done means either macOS support is implemented and documented, or the README clearly states that only Linux and Windows are supported.

Written by the indexing model from the issue text.