Windows cross resource actions now stage LLVM preprocessing tools and Windows SDK headers, use Linux temporary paths, and resolve icons/manifests to declared Bazel inputs. `mongo_config_header.py` invokes polyglot `.cmd`/`.bat` compiler wrappers through `/bin/sh` on POSIX workers. Correct the shell icon path and remove the stray semicolon in the resource version string.

Extracted from #63670. Targets master independently of #64507, using the toolchain inputs already merged in #64056. Native RC actions retain their original source and environment; regression tests cover both native and cross action planning plus real POSIX wrapper execution. Full LLVM resource compilation and native Windows execution remain pending CI validation.