Add test coverage for transpose, reverse, bool redux, select, diagonal-of-product at boundaries

Summary

• adjoint.cpp: Test transposeInPlace() at PacketSize boundary sizes for square and non-square dynamic matrices, exercising BlockedInPlaceTranspose remainder handling.
• array_reverse.cpp: Test reverseInPlace() (vector, matrix, colwise, rowwise) at PacketSize boundaries with element-by-element verification.
• redux.cpp: Extend boolean redux tests (all()/any()/count()) to vectorization boundary sizes (1-129) as column vectors, row vectors, and thin matrices.
• diagonal.cpp: Test (A*B).diagonal() lazy evaluation vs explicit product at boundary sizes, and .select() at vectorization boundaries with all three overloads.
• product_symm.cpp: Test symmetric matrix products at blocking boundary sizes (1..128) for float, double, and complex.

Test plan

• All new subtests pass locally (100%)
• Tests are deterministic and complete in < 1 second total
• Stable across 5 repeated runs

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