Add --fix-missing flag to handle Debian mirror issues

- Cleans apt cache before update to avoid stale data
- Adds --fix-missing flag to handle transient mirror synchronization issues
- Fixes hash sum mismatch errors during package installation
- Improves reliability when building on different mirrors

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Dockerfile

@@ -4,7 +4,11 @@ WORKDIR /app
 
 # Install system dependencies
 # Use --no-install-recommends and handle both amd64 and arm64 architectures
-RUN apt-get update && apt-get install -y --no-install-recommends \
+# Add --fix-missing to handle transient mirror issues
+RUN apt-get clean && \
+    rm -rf /var/lib/apt/lists/* && \
+    apt-get update && \
+    apt-get install -y --no-install-recommends --fix-missing \
     gcc \
     postgresql-client \
     libpq-dev \