[build] cpp compile during setup

[tscholak]

✨ Description

We can let setuptools build the cpp code. That's much cleaner, see #29 for more details.

Closes #29

🔍 Type of change

Select all that apply:

• [ ] 🐛 Bug fix (non-breaking change that addresses a specific issue)
• [ ] 🚀 New feature (non-breaking change that adds functionality)
• [ ] ⚠️ Breaking change (a change that could affect existing functionality)
• [ ] 📈 Performance improvement/optimization (improves speed, memory usage, or efficiency)
• [ ] 🛠️ Code refactor (non-functional changes that improve code readability, structure, etc.)
• [ ] 📦 Dependency bump (updates dependencies, including Dockerfile or package changes)
• [ ] 📝 Documentation change (updates documentation, including new content or typo fixes)
• [x] 🔧 Infrastructure/Build change (affects build process, CI/CD, or dependencies)

📝 Changes

List the key changes introduced in this PR:

1. Add cppbind11 dependency
2. Move cpp build to setup
3. Update Dockerfile

✅ Checklist

Make sure the following tasks are completed before submitting the PR:

General:

• [x] 📜 I have read and followed the contributing guidelines.
• [x] 🎉 The functionality is complete, and I have tested the changes.
• [ ] 📝 I have updated the documentation if needed.
• [x] ⚠️ The change does not introduce any new issues (e.g., runtime warnings, type checker errors, linting problems, unhandled edge cases).
• [x] 🧩 I have commented my code, especially in hard-to-understand areas.

Dependencies and Configuration:

• [x] 🐋 I have updated the Docker configuration or dependencies, if applicable.
• [x] 🔄 I have ensured compatibility with the existing setup after dependency changes.

Testing:

• [ ] 🧪 I have added or updated tests to cover my changes.
• [ ] ✔️ New and existing tests pass locally with my changes.
• [ ] 🚦 I have tested these changes on GPUs and verified training stability.
• [ ] 🏋️ I have tested the changes on realistic training workloads, if applicable.

Performance Impact:

• [ ] 📊 I have run benchmarks where applicable to evaluate the performance impact.
• [ ] ✅ The benchmarks show no performance regression.
• [ ] 🚀 The benchmarks indicate a potential performance improvement.
• [ ] ⚠️ The benchmarks indicate a potential performance degradation.
• [ ] 📈 I have provided benchmark results and detailed any performance impact below, if applicable.

📊 Performance Impact Details

N/A

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📝 Additional Notes

N/A

[tscholak]

Sounds like a good idea, I'll see to it

[tscholak]

Looks great, but how about we move the compile to [CORE]?

I looked into it. I couldn't figure out how to do it. If I do, I'll make another attempt. Right now it doesn't seem to be worth chasing this.