fix: data 엔진 host bootstrap을 분리한다

target module source만 먼저 준비하고 SIMD Setup은 WASI build에만 적용한다.
host GCC가 target 전용 flag를 받지 않도록 재현 builder 구조 계약을 추가한다.
검증: npm run test:contracts, npm test

Author: eddmpython

CHANGELOG.md

@@ -51,6 +51,8 @@ No unreleased public changes.
   isolated process group that is terminated as a whole. A remaining exact profile becomes a structured failure.
 - Digest-locked Python wrapper sources are checked out as LF on every platform, so fresh Windows runners verify
   the same supply-chain bytes as Linux and repository builds.
+- The data engine builder copies target module sources before the native bootstrap but applies its SIMD
+  `Setup.local` only to the WASI target build, keeping host GCC free of target-only flags.
 - V86 inspection reports readiness only after the engine event. A pre-ready timeout no longer calls unsafe
   partial-instance stop or destroy methods, while a ready instance retains the full drain, flush, and destroy
   path.

scripts/engineBuilder/buildOwnedEngine.mjs

@@ -51,10 +51,14 @@ async function download(url, path, sha256) {
   await verify(path, sha256);
 }
 
-async function prepareSetup(sourceDir, buildDir, profileInput) {
+async function prepareModuleSources(sourceDir, profileInput) {
   for (const module of profileInput.recipe.modules) {
     await copyFile(join(SCRIPT_DIR, module.source), join(sourceDir, "Modules", module.source));
   }
+}
+
+async function prepareSetup(sourceDir, buildDir, profileInput) {
+  await prepareModuleSources(sourceDir, profileInput);
   await mkdir(join(buildDir, "Modules"), { recursive: true });
   await copyFile(join(SCRIPT_DIR, profileInput.recipe.setupFile), join(buildDir, "Modules", "Setup.local"));
 }
@@ -100,7 +104,8 @@ async function main() {
   };
   const buildTriple = run(join(sourceDir, "config.guess"), [], { cwd: sourceDir, env: baseEnv, capture: true });
   const nativeBuildDir = join(sourceDir, "cross-build", buildTriple);
-  await prepareSetup(sourceDir, nativeBuildDir, profileBuild.input);
+  await prepareModuleSources(sourceDir, profileBuild.input);
+  await mkdir(nativeBuildDir, { recursive: true });
   run("../../configure", lock.configureArgs, {
     cwd: nativeBuildDir,
     env: { ...baseEnv, CFLAGS: lock.cflags },

tests/contracts/engineBuilder.mjs

@@ -218,6 +218,8 @@ export async function assertOwnedEngineBuilder() {
     && windowsBuilder.includes("generateWindowsCrossSysconfigData")
     && windowsBuilder.includes("ownedBuildDetailsArguments"),
     "Windows owned engine build does not generate platform metadata");
-  assert(linuxBuilder.includes("ownedBuildDetailsArguments"),
-    "Linux owned engine build does not generate platform metadata");
+  assert(linuxBuilder.includes("ownedBuildDetailsArguments")
+    && linuxBuilder.includes("prepareModuleSources(sourceDir, profileBuild.input)")
+    && !linuxBuilder.includes("prepareSetup(sourceDir, nativeBuildDir"),
+  "Linux owned engine host bootstrap incorrectly applies target-only native modules");
 }