fix(build): Ensure output files are world-readable for nginx serving

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/build.sh

@@ -193,6 +193,9 @@ build_firmware() {
 
     rm -rf "$tmpfiles"
 
+    # Ensure output files are world-readable (served by nginx)
+    chmod 644 "${PROJECT_DIR}/output/"* 2>/dev/null || true
+
     echo ""
     echo "Build complete! Firmware images:"
     ls -lh "${PROJECT_DIR}/output/"*.bin 2>/dev/null || true