fix: add missing WORKDIR /app in production stage

The multi-stage build conversion in livekit-examples#56 moved WORKDIR /app into the
build stage, but each FROM resets the working directory. Without
WORKDIR in the production stage, CMD runs from / and fails with
"Failed to spawn: src/agent.py - No such file or directory".

This matches the CLI's embedded template (livekit-cli PR #789).

Author: ShayneP

Dockerfile

@@ -68,6 +68,8 @@ RUN adduser \
 # This avoids expensive recursive chown and excludes build tools from the final image
 COPY --from=build --chown=appuser:appuser /app /app
 
+WORKDIR /app
+
 # Switch to the non-privileged user for all subsequent operations
 # This improves security by not running as root
 USER appuser