fix(docker): copy Python packages to root home directory

Since API container runs as root (for Docker socket access),
copy Python packages to /root/.local instead of /home/appuser/.local
so uvicorn and other dependencies are in PATH.

apps/api/Dockerfile

@@ -41,8 +41,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     && rm -rf /var/lib/apt/lists/*
 
 # Copy dependencies from builder
-COPY --from=builder /root/.local /home/appuser/.local
-ENV PATH=/home/appuser/.local/bin:$PATH
+COPY --from=builder /root/.local /root/.local
+ENV PATH=/root/.local/bin:$PATH
 
 # Copy application code
 COPY --chown=appuser:appgroup . .