Add setup.sh to pre-cache Whisper model during build

HF Spaces caches the build layer, so downloading during setup.sh
avoids re-downloading the model on every cold start.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

setup.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+# Runs during HF Spaces build phase (build layer is cached).
+# Pre-downloads the Whisper model so cold starts don't re-download it.
+# WHISPER_MODEL_ID is available as an env var at build time if set in Space secrets.
+MODEL=${WHISPER_MODEL_ID:-openai/whisper-small}
+echo "Pre-caching $MODEL ..."
+python -c "
+from huggingface_hub import snapshot_download
+import os
+snapshot_download('${MODEL}', repo_type='model')
+print('Done.')
+"