Fix piper: keep all bundled libs, register with ldconfig

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

Dockerfile

@@ -7,9 +7,11 @@ RUN apt-get update && apt-get install -y --no-install-recommends wget ca-certifi
 
 RUN wget -qO /tmp/piper.tar.gz \
       https://github.com/rhasspy/piper/releases/download/2023.11.14-2/piper_linux_x86_64.tar.gz \
-    && tar -xzf /tmp/piper.tar.gz -C /tmp \
-    && mv /tmp/piper/piper /usr/local/bin/piper \
-    && rm -rf /tmp/piper*
+    && tar -xzf /tmp/piper.tar.gz -C /usr/local/lib \
+    && ln -s /usr/local/lib/piper/piper /usr/local/bin/piper \
+    && echo /usr/local/lib/piper > /etc/ld.so.conf.d/piper.conf \
+    && ldconfig \
+    && rm /tmp/piper.tar.gz
 
 RUN mkdir -p /app/voices \
     && wget -qO /app/voices/en_US-lessac-medium.onnx \