fix: stamp build commit metadata

scripts/write-build-info.ts

@@ -0,0 +1,48 @@
+import { execSync } from "node:child_process";
+import fs from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const rootDir = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
+const distDir = path.join(rootDir, "dist");
+const pkgPath = path.join(rootDir, "package.json");
+
+const readPackageVersion = () => {
+  try {
+    const raw = fs.readFileSync(pkgPath, "utf8");
+    const parsed = JSON.parse(raw) as { version?: string };
+    return parsed.version ?? null;
+  } catch {
+    return null;
+  }
+};
+
+const resolveCommit = () => {
+  const envCommit = process.env.GIT_COMMIT?.trim() || process.env.GIT_SHA?.trim();
+  if (envCommit) return envCommit;
+  try {
+    return execSync("git rev-parse HEAD", {
+      cwd: rootDir,
+      stdio: ["ignore", "pipe", "ignore"],
+    })
+      .toString()
+      .trim();
+  } catch {
+    return null;
+  }
+};
+
+const version = readPackageVersion();
+const commit = resolveCommit();
+
+const buildInfo = {
+  version,
+  commit,
+  builtAt: new Date().toISOString(),
+};
+
+fs.mkdirSync(distDir, { recursive: true });
+fs.writeFileSync(
+  path.join(distDir, "build-info.json"),
+  `${JSON.stringify(buildInfo, null, 2)}\n`,
+);