HaarMatrix is not exported as a command

Maybe I'm just being stupid, but the readme makes it sound like `HaarMatrix` is a command that I can run. But appears nowhere in the source! (Let alone exported)

Start by searching the README and source for `HaarMatrix`, then check how commands are exported. Confirm whether the README promises a runnable command or whether the missing entry is an implementation gap; done means the documentation and package behavior agree, with a focused test if command behavior is intended.

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