Replace build backend with hatchling

[MilkClouds]

📝 PR Description

Purpose

setuptools fail to install package correctly. hatch, widely used modern, extensible Python project manager does not have error.

Rationale of PR: I did tried to use code from dexbotic but fail with setuptools :(

$ uv pip install "git+https://github.com/Dexmal/dexbotic.git@0.2.0"
Resolved 183 packages in 582ms
Uninstalled 2 packages in 208ms
Installed 2 packages in 138ms
 ~ decord==0.6.0
 - dexbotic==0.2.0 (from git+https://github.com/MilkClouds/dexbotic.git@42f72859dfe48bb4c30a09ab151a018c2ca0700a)
 + dexbotic==0.2.0 (from git+https://github.com/Dexmal/dexbotic.git@932192c796c030babf4f10e3dcd6da27d093fc05)
$ python -c "import dexbotic.model"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named 'dexbotic.model'

$ uv pip install "git+https://github.com/MilkClouds/dexbotic.git@build-with-hatch"
Resolved 183 packages in 648ms
Uninstalled 2 packages in 78ms
Installed 2 packages in 191ms
 ~ decord==0.6.0
 - dexbotic==0.2.0 (from git+https://github.com/Dexmal/dexbotic.git@932192c796c030babf4f10e3dcd6da27d093fc05)
 + dexbotic==0.2.0 (from git+https://github.com/MilkClouds/dexbotic.git@42f72859dfe48bb4c30a09ab151a018c2ca0700a)
$ python -c "import dexbotic.model" # do not fail
$ 

Change Summary

Replaced setuptools to hatch

Benchmark Evidence

Already stated on above.

Reproduce Command

Already stated on above.

Dependencies

None

Environment

N/A

✔️ Review Checklist (must all be checked)

• No breaking changes to core interfaces (VLA API / Dexdata)
• No redundant implementation (checked existing modules first)
• Code follows existing design link
• Local validation completed with commands + expected output
• Benchmark evaluation completed and attached
• No regressions observed
• No new dependencies or all new dependencies listed
• Merges cleanly on current main and builds successfully