fix(hub): give the voice and whisper directories the search bit

ADD --chmod=0644 also set mode 0644 on /opt/voices and /opt/whisper, so the non-root hub found no voice and no whisper.cpp and the radio stayed silent. The settings page and the 503 replies now name the missing piece.

🎯 Fix: 90 %
💥 Break: 3 %
💸 Cost: 98 %
⏱️ Time: 96 %
🛡️ Security: 100 %
🏆 Score: 93
🚦 Gate: ✅ 90/5, cost and time <= 100, security 100 %

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

hub/Dockerfile

@@ -31,6 +31,8 @@ ADD --checksum=sha256:c577b9a86e7e048a0b7eada054f4dd79a56bbfa911fbdacf900ac5b567
     https://huggingface.co/ggerganov/whisper.cpp/resolve/5359861c739e955e79d9a303bcbc70fb988958b1/ggml-base-q8_0.bin \
     /opt/whisper/ggml-base-q8_0.bin
 COPY --from=whisper /out/whisper-cli /opt/whisper/whisper-cli
+# ADD --chmod=0644 also gives the directories it creates mode 0644; without the search bit the non-root hub finds no voice and no whisper.cpp
+RUN chmod 0755 /opt/voices /opt/whisper
 
 COPY server.py /app/server.py
 COPY kvb_hub /app/kvb_hub