Proposal: Remove `site/` dir and flatten structure now that sphinx is no longer around #425

Job	Run time
ubuntu-latest with Python 3.13	1m 19s
ubuntu-latest with Python 3.11 and latest released version of dependencies	1m 18s
ubuntu-latest with Python 3.10 and oldest versioned dependencies	1m 20s
macos-latest with Python 3.13	1m 43s
ubuntu-latest with Python 3.12 and latest or pre-release version of dependencies	1m 27s
ubuntu-latest with Python 3.14 and developer versioned dependencies	2m 2s
windows-latest with Python 3.13	2m 38s
	11m 47s

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