[grade=B] DC-072: Enable source maps in production esbuild bundles

Add sourcemap: 'both' to esbuild.transform — emits inline + external .map
files for production debugging. Stack traces now point to real source lines.

DC-090: Already resolved — Dockerfile pins node:20.11.1-alpine3.19 (specific).

status/build.js

@@ -149,13 +149,18 @@ async function build() {
     const concatenated = parts.join(';\n');
 
     // Minify with esbuild (safe to re-minify already-minified code like driver.min.js)
-    const { code } = await esbuild.transform(concatenated, {
+    // DC-072: sourcemap='both' emits inline + external .map for production debugging
+    const { code, map } = await esbuild.transform(concatenated, {
       minify: true,
       target: 'es2020',
+      sourcemap: 'both',
     });
 
     const outPath = path.join(DIST, outName);
     fs.writeFileSync(outPath, code);
+    if (map) {
+      fs.writeFileSync(outPath + '.map', map);
+    }
 
     const rawSize = (Buffer.byteLength(concatenated) / 1024).toFixed(1);
     const minSize = (Buffer.byteLength(code) / 1024).toFixed(1);