#7271 derives the Windows `.exe` suffix from a parse-time `go env GOOS`,
which cannot see GOOS passed as a Make variable: `make build GOOS=windows`
still emits PE binaries named `bin/server`, `bin/multica`, `bin/migrate` —
the exact artifacts #7255 reported as unable to re-exec themselves. The
top-level `export` puts the Make variable in the recipe's environment, so
`go build` targets Windows while the name says otherwise.
Reading `$(GOOS)` first covers both invocation forms, and making the
assignment target-specific keeps the toolchain probe on `build` alone: a
global assignment is expanded on every make invocation — `export` expands
even a recursive one — so `make help` / `make clean` printed
`go: Command not found` on checkouts without Go.
Adds scripts/makefile-build.test.sh to pin both invocation forms, the
non-Windows names, and the no-Go case, wired into the backend CI job that
already runs the other Makefile-adjacent shell tests.
Co-authored-by: Bohan-J <[email protected]>
Co-authored-by: multica-agent <[email protected]>
