Resolve ZIP write completion on output close

Wait for the write stream close event in zipFolder to ensure the file
descriptor is flushed and closed before proceeding. This avoids rare
truncated ZIPs on fast CI runners. Keep error and warning handling
unchanged.

Author: PeterDaveHello

build.mjs

@@ -432,16 +432,26 @@ async function zipFolder(dir) {
         reject(err)
       }
     }
+    const done = () => {
+      if (!settled) {
+        settled = true
+        resolve()
+      }
+    }
     output.once('error', fail)
     archive.once('error', fail)
     archive.on('warning', (err) => {
       // Log non-fatal archive warnings for diagnostics
       console.warn('[build][zip] warning:', err)
     })
+    // Resolve on close to ensure FD is flushed and closed
+    output.once('close', done)
+    // Ensure close is emitted after finish on some fast runners
     output.once('finish', () => {
-      if (!settled) {
-        settled = true
-        resolve()
+      try {
+        if (typeof output.close === 'function') output.close()
+      } catch (_) {
+        // ignore
       }
     })
     archive.pipe(output)