Whisper model path should survive brew upgrades

[fitz123]

Problem

brew upgrade whisper-cpp replaces the entire Cellar directory, deleting the manually downloaded ggml-medium.bin model (~1.5GB). Voice transcription silently breaks until someone notices.

Root cause: voice.ts defaults to /opt/homebrew/share/whisper-cpp/ggml-medium.bin which lives inside the Cellar and gets wiped on upgrades.

Evidence: Model disappeared after whisper-cpp upgrade to 1.8.4 on Apr 4. Voice messages stopped working.

Proposed fix

Change the default WHISPER_MODEL path from the Cellar location to a persistent location outside brew's control:

// before
export const WHISPER_MODEL = process.env.WHISPER_MODEL ?? "/opt/homebrew/share/whisper-cpp/ggml-medium.bin";

// after  
export const WHISPER_MODEL = process.env.WHISPER_MODEL ?? `${process.env.HOME}/.minime/models/ggml-medium.bin`;

Workaround applied: Model copied to ~/.minime/models/ggml-medium.bin, symlinked back to Cellar path. Works but fragile — symlink itself gets replaced on next upgrade.