Add Mundwerk

[bkindler]

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://mundwerkapp.de
3. Why should this project be added: Mundwerk is a native macOS menu bar dictation app that runs whisper.cpp locally on Apple Silicon. Fits the rule "Leveraging local, specialised ML models as part of a larger process is fine" — Whisper is the local STT backend, not an LLM/chatbot wrapper. Native Swift (no Electron). Commercial with a 7-day free trial without account.
4. End all descriptions with a full stop/period
5. Entry is ordered alphabetically (placed between MenubarX and OmniFocus in Productivity)
6. Appropriate icon(s) added if applicable — none needed (commercial, no OSS, no freeware)