Add MetaClean to desktop privacy tools

[Moresyl]

Summary

Adds MetaClean to Privacy Tools → Desktop as an open-source, cross-platform tool for removing private metadata locally.

Requirements review

• Clear privacy policy: the README documents local-only processing, no upload API, no telemetry, safe-copy defaults, atomic writes, and explicit format limits.
• No tracking: MetaClean has no project website or analytics; releases and documentation are hosted on GitHub.
• Open source: MIT-licensed Rust/Tauri source is fully available for review.
• Description format: one sentence explaining what the tool does, its MIT license, supported platforms, offline behavior, and lack of telemetry.

Verification

The repository includes CI, a security policy, test coverage evidence, a real application screenshot, and a published v0.1.0 release with seven GitHub Actions-built Windows, macOS, and Linux packages.