fix(verify): gate JIT verification to amd64 until trampolines are hardened

cmd/gasm/main.go

@@ -1091,9 +1091,11 @@ each entry reproduces.
 	}
 	path := set.Arg(0)
 	targetArch := arch.FromFilename(path)
-	// JIT execution requires the host CPU to match the kernel's
-	// architecture; on any other host only the toolchain comparisons run.
-	if targetArch != hostArch() {
+	// JIT execution is enabled for amd64 kernels on amd64 hosts.  The
+	// non-amd64 execution trampolines are implemented but not yet
+	// runtime-hardened, so other kernels take the toolchain-comparison
+	// path, which needs no execution.
+	if targetArch != arch.AMD64 || hostArch() != arch.AMD64 {
 		switch targetArch {
 		case arch.RISCV:
 			// RISC-V: ground-truth only (no JIT on non-RISC-V hosts).