按建议，继续工作

结论：已新增 G53 机床坐标正向 fixture 和增量模式拒绝 fixture，固定 vendored LinuxCNC find_ends()/convert_straight() 行为；native probe 全量验证通过。

wasm-port/docs/compatibility-validation.md

@@ -67,6 +67,7 @@ Positive G-code fixtures currently cover:
 - position parameters
 - canned cycles
 - coordinate offsets
+- G53 machine-coordinate motion
 - feed and motion control modes
 - probing
 - threading and rigid tap
@@ -84,6 +85,7 @@ Negative fixtures currently cover:
 - zero-feed `G1`
 - arc radius mismatch
 - zero-radius arc
+- G53 incremental-mode rejection
 - read-only named parameter writes
 - read-only numbered parameter writes
 - missing tool