feat: Dev Experience Improvements (Split Docker Build, Symlinks)

[diangogav]

Summary

Optimized Docker build process locally and for production.

Changes

• Split Dockerfile: Created Dockerfile.base for heavy dependencies (cacheable) and Dockerfile for app logic.
• Symlink Optimization: Reduced image size (approx 1GB saved) by using relative symlinks for duplicate script folders.
• DevContainer: Added DevContainer support (detached DB).
• Scripts: Updated deploy.sh to handle the split build and cache busting.
• Docs: Updated README.md and added design docs.

Verification

• deploy.sh runs successfully.
• docker-compose setup validated (ports/env).