[tannevaled]

Generator.Choice, RandomState.Choice and random.Choice allocated twice per drawn element. The gather (takeAxis) sliced reflect.Values for every index, and each Value.Slice allocates. It now copies whole slabs through a byte view of the source and the result: one code path for all 13 dtypes, none of which hold pointers.

Closes #103

Allocations for 100 000 draws from a 1000-element array, from go test -run TestPerf -perf.record (exact under any load; docs/perf.json and docs/perf-table.md are updated):

row	before	after
random.Generator.Choice	200 013	13
random.RandomState.Choice	200 012	12
random.Choice	200 012	12

NumPy makes one allocation (the result); the 12–13 left are the fixed cost of the index draw and the result array. Timing is deferred: the 1-minute load here was 11, above the harness's limit of 8.

• TestChoiceAllocsConstant: 100 and 10 000 draws must cost the same number of allocations, along axis 0 of a 1-D array and along axis 1 of a 2-D one. On the old code it fails with 213 vs 20 013 and 2 014 vs 200 014.
• The values are unchanged: the NumPy golden tests in random/numpy_test.go pass.
• random stays at 100 % statement coverage.
• SECURITY.md: an audit-log entry for the unsafe.Slice view.

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