fix: add libc6-dev to Docker compile stage for pyzint C extension

The python:3.12.10-slim base image no longer includes C standard
library headers. Add libc6-dev so pyzint and other C extensions
can compile during the Docker build.

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

Author: danh91

docker/api/Dockerfile

@@ -5,7 +5,7 @@ ARG REQUIREMENTS="requirements.txt"
 ARG REGISTRY_TOKEN
 ARG REGISTRY_TOKEN_NAME
 
-RUN apt-get update -y && apt-get install -y --no-install-recommends gcc \
+RUN apt-get update -y && apt-get install -y --no-install-recommends gcc libc6-dev \
     && rm -rf /var/lib/apt/lists/*
 
 RUN python -m venv /karrio/venv

docker/insiders/Dockerfile

@@ -3,7 +3,7 @@ FROM python:3.12.10-slim AS compile-image
 
 ARG REQUIREMENTS=./source.requirements.insiders.txt
 
-RUN apt-get update -y && apt-get install -y --no-install-recommends gcc \
+RUN apt-get update -y && apt-get install -y --no-install-recommends gcc libc6-dev \
     && rm -rf /var/lib/apt/lists/*
 
 RUN python -m venv /karrio/venv