fix(#374): add pip.conf to coordinator Docker build for private registry

The Docker build failed because pip couldn't find mosaicstack-telemetry
from the private Gitea PyPI registry. Copy pip.conf into the image so
pip resolves the extra-index-url during docker build.

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

apps/coordinator/Dockerfile

@@ -9,8 +9,9 @@ RUN apt-get update && \
     build-essential \
     && rm -rf /var/lib/apt/lists/*
 
-# Copy dependency files
+# Copy dependency files and private registry config
 COPY pyproject.toml .
+COPY pip.conf /etc/pip.conf
 
 # Create virtual environment and install dependencies
 RUN python -m venv /opt/venv