v0.28.6

Declare OpenMP loop variable outside the for-init for MSVC

MSVC's OpenMP 2.0 implementation rejects declaring the loop variable
inside the parallel-for init-expression (`for (int i = 0; ...)`),
even though MSVC's plain C/C++ accepts it. The OpenMP 2.0 spec
requires the init to be `var = lb`, not `type var = lb`. Move the
declaration of li_s and l_size_i above the pragma so the for-init is
a bare assignment.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>