Runs a native zig build (the iOS simulator/device binary, the Android per-ABI objects, Zigler NIF cross-compiles) and turns its result into :ok or an error that names what broke.

Two things this owns (MOB-344):

• Warnings are not failures. Zig's build runner prints every step that wrote to stderr in its failure layout — step tree, a w marker and a failed command: line — even when the step exited 0. A plugin NIF whose clang compile emits one warning therefore read as a failed compile while the build went on to succeed. We run zig with ZIG_BUILD_ERROR_STYLE=minimal (unless the caller's environment already chose a style), which drops that command-line context, and list the steps that only warned after a successful build.

• A failure names the plugin and the compiler error. zig's own exit line only says the build failed. On a non-zero exit we parse the captured output for the failing steps and the compiler error: lines, and attribute them to the plugin whose NIF source failed, so the ✗ <platform> native build failed: line says which plugin to fix.

The output is still streamed live; it's captured alongside for the parse.