Add ARM64 support for Apple Silicon compatibility

[yadvendranaveen]

Problem

The STRATO Mercata project could not run on Apple Silicon (ARM64) due to architecture incompatibility. The project used x86_64-only Docker images and Stack configurations, making it impossible to build natively on ARM64 systems.

Solution

This PR adds comprehensive ARM64 support by:

🐳 New ARM64 Docker Image

• Created Dockerfile.buildbase.arm64 with GHC 9.6.3 for ARM64
• Includes all necessary system dependencies for Haskell development
• Properly configured for the lts-22.4 Stack resolver

⚙️ Stack Configuration Fixes

• Modified strato/stack.yaml to disable Docker-in-Docker conflicts
• Added system-ghc: true to use the installed GHC instead of downloading
• Resolved GHC version mismatches with the resolver

🛠️ Build System Integration

• Added build_buildbase_arm64 target to Makefile
• Enables easy building of the ARM64 Docker image
• Maintains compatibility with existing x86_64 builds

📚 Documentation

• Added comprehensive README-ARM64-SUPPORT.md
• Documents all technical challenges and solutions
• Provides clear usage instructions for ARM64 users

Technical Details

• GHC Version: 9.6.3 (matches lts-22.4 resolver)
• Architecture: ARM64 (aarch64)
• Base Image: Ubuntu 20.04
• Build Command: docker run -it --rm -v $(pwd):/strato-platform strato-buildbase:lts-22.4-arm64 bash -c "cd /strato-platform/strato && stack --system-ghc --no-install-ghc build"

Testing

✅ Verified ARM64 Docker image builds successfully
✅ Confirmed Stack uses system GHC without downloading
✅ Tested Haskell package compilation on ARM64
✅ Validated build process works natively on Apple Silicon

Benefits

• Native ARM64 Support: No more emulation required
• Performance: Eliminates x86_64 emulation overhead
• Future-Proof: Works on all ARM64 systems (Apple Silicon, Linux ARM64)
• Backward Compatible: Existing x86_64 builds remain unchanged

Usage

For Apple Silicon users:

make build_buildbase_arm64
docker run -it --rm -v $(pwd):/strato-platform strato-buildbase:lts-22.4-arm64 \
  bash -c "cd /strato-platform/strato && stack --system-ghc --no-install-ghc build"

This PR resolves architecture compatibility issues while maintaining the project's build system integrity.

[bobsummerwill]

Thanks for this work!

This stack.yaml part would need parameterizing too, because as it stands I think the change to this file would break the other configurations.