将最小解释器验证改为fixture驱动

结论：最小解释器 harness 改为读取 G-code fixture，并通过 expected canonical event fixture 验证 G0/G1/feed 输出，后续扩展覆盖可直接新增 fixture。检查：git diff --check 通过；wasm-port/tests/native/verify_native_probes.sh 通过。

wasm-port/docs/porting-steps-standalone.md

@@ -351,6 +351,9 @@ Current verified progress:
   `STRAIGHT_TRAVERSE` canonical event for `G0 X1.0 Y2.0`, plus
   `SET_FEED_RATE` and `STRAIGHT_FEED` canonical events for
   `G1 X3.0 Y4.0 F120.0`.
+- The same validation is now fixture-driven through
+  `tests/fixtures/gcode/minimal_linear.ngc` and
+  `tests/fixtures/canon/minimal_linear.events`.
 - This proves the current extracted interpreter slice can parse and execute a
   simple traverse and feed move through a standalone canonical event sink.
 
@@ -651,7 +654,7 @@ Keep these documents under `wasm-port/docs/`:
 Continue expanding the standalone interpreter core from the verified minimal
 traverse path:
 
-1. introduce a fixture-driven G-code validation script under `tests/fixtures/`,
+1. add another fixture for incremental mode and modal carry-forward,
 2. replace the temporary minimal `convert_g()` implementation with thin
    wrappers around more vendored interpreter conversion code,
 3. keep all source changes inside `wasm-port/` and leave `../linuxcnc/`