Improves Docker build performance and security through better layer caching,
dependency pre-building, and a minimal non-root runtime container.
- Add cargo-chef for Rust dependency caching across demo and server builds
- Separate planner and builder stages for optimal layer reuse
- Use pnpm with frozen lockfile for reproducible frontend builds
- Switch to debian:12-slim runtime with non-root user (uid 1000)
- Add health check endpoint monitoring
- Strip release binaries to reduce image size
- Pre-compress frontend assets during build
