参考所有分组，完成尽量多的内容。禁止顺手扩功能 smoke

结论：收敛第 3/5/6 组 OPFS/browser 约束，test-native guardrail 明确要求 wasm-core OPFS 路径拒绝反斜杠和 NUL 字符，防止 browser WASM filesystem 路径逃逸；未扩展 smoke 功能。验证：./test-native.sh、./test-linuxcnc-source-link.sh 均通过。

test-native.sh

@@ -267,6 +267,8 @@ grep -F 'async function statOpfsEntry(workspacePath, relativePath)' web/src/wasm
 grep -F 'async function readOpfsDirectoryTree(workspacePath, relativePath, relativeRoot = "")' web/src/wasm-core.js >/dev/null
 grep -F 'function readWasmDirectoryTree(module, rootPath, relativeRoot = "")' web/src/wasm-core.js >/dev/null
 grep -F 'function writeWasmFileReplacingPath(module, path, data)' web/src/wasm-core.js >/dev/null
+grep -F 'path.includes("\\")' web/src/wasm-core.js >/dev/null
+grep -F 'path.includes("\0")' web/src/wasm-core.js >/dev/null
 grep -F '`${LINUXCNC_DEFAULT_PARAMETER_FILE}.bak`' web/src/wasm-core.js >/dev/null
 grep -F 'export type WasmModuleOptions' web/src/wasm-core.d.ts >/dev/null
 grep -F 'printErr?: (text: string) => void;' web/src/wasm-core.d.ts >/dev/null