feat: Dockerfiles for pipeline, api, and cron containers

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

cron/Dockerfile

@@ -0,0 +1,17 @@
+FROM python:3.12-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libsndfile1 && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+COPY pyproject.toml .
+RUN pip install --no-cache-dir torch --index-url https://download.pytorch.org/whl/cpu && \
+    pip install --no-cache-dir resemblyzer scipy numpy httpx pydantic-settings
+
+COPY app/ app/
+
+# Pre-download resemblyzer model
+RUN python -c "from resemblyzer import VoiceEncoder; VoiceEncoder()"
+
+ENV PYTHONUNBUFFERED=1
+CMD ["python", "-m", "app.cron.main"]