转向直接移植LinuxCNC源程序

结论：明确禁止继续扩展自写 CNC 主体语义，最小 runtime 仅保留为迁移探针；新增 interp_convert.cc 源码直连编译探针，并以最小 emcStatus 状态边界 shim 暴露 native runtime 阻塞点。检查：git diff --check 通过；wasm-port/tests/native/verify_native_probes.sh 通过，linuxcnc_interp_convert_source_probe exitcode=0。

wasm-port/runtime/core/linuxcnc_wrap/linuxcnc_emc_status_probe.cpp

@@ -0,0 +1,4 @@
+#include "nml_intf/emc.hh"
+
+static EMC_STAT standalone_emc_status;
+EMC_STAT *emcStatus = &standalone_emc_status;

wasm-port/runtime/core/shims/nml_intf/emc.hh

@@ -1,7 +1,18 @@
 #pragma once
 
-// Minimal shim for the standalone INI parser build.
+// Minimal shim for standalone interpreter source probes.
 enum EmcJointType : int {
     EMC_LINEAR = 1,
     EMC_ANGULAR = 2,
 };
+
+class EMC_STAT {
+public:
+    struct Motion {
+        struct Traj {
+            double linearUnits = 1.0;
+        } traj;
+    } motion;
+};
+
+extern EMC_STAT *emcStatus;