GeezerVison

fmt 10 made formatter::format() const and fmt 11 moved fmt::join to ranges.h, so ArrayFire no longer builds against a system fmt on Arch, Homebrew, or recent Ubuntu:

error C2662: 'fmt::v11::formatter<arrayfire::common::Version,char,void>::format' ... cannot convert 'this' pointer from 'const formatter' to 'formatter &'

Every custom formatter's format() is now const, ranges.h is included where join is used, and the Version formatter combines its parsed flags into locals instead of mutating them, so {:Mm} still renders 1.2 rather than 1.2.0 (the patch on #3596 lost that, and the OpenCL backend uses it for -cl-std). The two debug headers that nothing includes also stop naming spdlog's bundled fmt directly. Built the CPU backend against fmt 11.2 / spdlog 1.15 and against the pinned fmt 8.1 / spdlog 1.9, and the CUDA backend against fmt 8; a standalone probe compiles the CUDA and debug formatter headers under both fmt versions with identical output. The OpenCL file was not built here. Fixes #3692 and #3596.