Add OpenQuack

[larryxiao]

0. I have read the Contribution Guidelines
1. I confirm that I have read and understood the sections about "AI"-adjacent software
2. Project URL: https://github.com/larryxiao/openquack
3. Why should this project be added: OpenQuack is a privacy-first local voice dictation menu bar app for macOS — push a hotkey, speak, the transcript is pasted at the cursor. It runs WhisperKit on Apple Silicon, supports 99 Whisper languages, and never sends audio or text off the device. MIT-licensed, no signup, no telemetry. It's a specialised-ML-as-part-of-a-larger-process app (per the contribution rules), not an LLM/agent wrapper — Whisper is the model, the rest is a Mac menu-bar app around it. Inserted alphabetically in the Audio section between Murmur and Plug.
4. End all descriptions with a full stop/period
5. Entry is ordered alphabetically
6. Appropriate icon(s) added if applicable (OSS, freeware)