Add Cython build infra + initial extension module #57

Job	Run time
Docs, Examples, and Eval	3m 40s
Conda Python 3.10 on macos-latest	3m 39s
Measure Cython Coverage	3m 30s
Conda Python 3.10 on macos-14	3m 28s
Minimal Supported Dependencies	19s
Conda Python 3.10 on windows-latest	3m 35s
Conda Python 3.10 on ubuntu-latest	3m 39s
Vanilla Python 3.10 on windows-latest	1m 21s
Conda Python 3.11 on macos-latest	3m 40s
Vanilla Python 3.10 on ubuntu-latest	40s
Conda Python 3.11 on macos-14	3m 23s
Vanilla Python 3.10 on macos-14	44s
Conda Python 3.11 on windows-latest	3m 34s
Vanilla Python 3.11 on windows-latest	2m 32s
Vanilla Python 3.11 on ubuntu-latest	45s
Conda Python 3.11 on ubuntu-latest	3m 39s
Vanilla Python 3.11 on macos-14	17s
Test Suite Results	1s
	42m 26s

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