Merge branch 'main' into binyli/unique-qp-and-gid-index

Resolve conflicts in env.hpp, env_py.cpp, and env.cpp by combining both
branches' additions: keep main's MSCCLPP_FORCE_DISABLE_GDR field and
this branch's -1 sentinel default for MSCCLPP_IB_GID_INDEX.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/csrc/env_py.cpp

@@ -28,6 +28,7 @@ void register_env(nb::module_& m) {
       .def_ro("force_nccl_fallback_operation", &Env::forceNcclFallbackOperation)
       .def_ro("nccl_symmetric_memory", &Env::ncclSymmetricMemory)
       .def_ro("force_disable_nvls", &Env::forceDisableNvls)
+      .def_ro("force_disable_gdr", &Env::forceDisableGdr)
       .def_ro("ib_gid_index", &Env::ibGidIndex);
 
   m.def("env", &env);